fix(deps): update dependency sanitize-html to v2.17.4 [security]

[renovate]

This PR contains the following updates:

Package	Change	Age	Confidence
sanitize-html (source)	2.15.0 → 2.17.4

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Apostrophe has default XSS via xmp raw-text passthrough in sanitize-html

CVE-2026-44990 / GHSA-rpr9-rxv7-x643

More information

Details

Summary

Under the default configuration, sanitize-html can turn attacker-controlled content inside a disallowed xmp element into live HTML or JavaScript. This is a sanitizer bypass in the default disallowedTagsMode: 'discard' path and can lead to stored XSS in applications that render sanitized output back to users.

Details

In sanitize-html@2.17.3, the default nonTextTags list includes only script, style, textarea, and option in index.js lines 138-142. That means disallowed xmp tags are not treated as "drop the entire contents" tags.

Later, in the ontext handler at index.js lines 569-577, the code special-cases textarea and xmp and appends their text content directly to the output without escaping:

} else if ((options.disallowedTagsMode === 'discard' || options.disallowedTagsMode === 'completelyDiscard') && (tag === 'textarea' || tag === 'xmp')) {
  result += text;
}

Because htmlparser2 treats xmp as a raw-text element, markup inside xmp is parsed as text on input but becomes live markup again once it is appended unescaped to the sanitized output.

This creates a default sanitizer bypass. For example, a disallowed <xmp> wrapper can be used to smuggle <script> or event-handler payloads through sanitization.

The README also appears to contradict the implementation. In the "Discarding the entire contents of a disallowed tag" section, the documented exception list names only style, script, textarea, and option, and does not mention xmp.

PoC

Tested locally against sanitize-html@2.17.3 on Node.js v25.2.1.

1. Install the package:

npm install sanitize-html

2. Run the following script:

const sanitizeHtml = require('sanitize-html');

console.log(sanitizeHtml('<xmp><script>alert(1)</script></xmp>'));
console.log(sanitizeHtml('<xmp><img src=x onerror=alert(1)></xmp>'));
console.log(sanitizeHtml('<xmp><svg><script>alert(1)</script></svg></xmp>'));

3. Observed output:

<script>alert(1)</script>
<img src=x onerror=alert(1)>
<svg><script>alert(1)</script></svg>

4. Render any of the returned strings in a browser context that trusts sanitize-html output, for example:

const dirty = '<xmp><script>alert(1)</script></xmp>';
const clean = sanitizeHtml(dirty);

If clean is inserted into the DOM or stored and later rendered as trusted HTML, the attacker-controlled script executes.

Impact

This is a cross-site scripting vulnerability in the default sanitizer behavior. Any application that uses sanitize-html defaults and then renders the returned HTML as trusted output is impacted. A remote attacker who can submit HTML content can trigger execution of arbitrary JavaScript in another user's browser when that content is viewed.

Severity

• CVSS Score: 9.3 / 10 (Critical)
• Vector String: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N

References

• https://github.com/apostrophecms/apostrophe/security/advisories/GHSA-rpr9-rxv7-x643
• https://github.com/apostrophecms/apostrophe/issues/5418
• https://github.com/apostrophecms/apostrophe/commit/8d4c882b4ed3a7ce802cd87f89f0c1cb7482b8c2
• https://github.com/advisories/GHSA-rpr9-rxv7-x643

This data is provided by the GitHub Advisory Database (CC-BY 4.0).

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Release Notes

apostrophecms/apostrophe (sanitize-html)

v2.17.4

Changes

• sanitize-html and launder now share a single implementation of naughtyHref, based on that which previously existed in sanitize-html.

Security

• Security vulnerability: the xmp tag could be used to pass forbidden markup through sanitize-html, even when xmp itself is not explicitly allowed All users of sanitize-html should update immediately. Thanks to Vincenzo Turturro for reporting the vulnerability.

v2.17.3

Compare Source

Security

• Fix vulnerability introduced in version 2.17.2 that allowed XSS attacks if the developer chose to permit option tags. There was no vulnerability when not explicitly allowing option tags.

v2.17.2

Compare Source

Changes

• Upgrade htmlparser2 from 8.x to 10.1.0. This improves security by correctly decoding zero-padded numeric character references (e.g., &#​0000001) that previously bypassed javascript: URL detection. Also fixes double-encoding of entities inside raw text elements like textarea and option.

v2.17.1

Compare Source

Fixes

• Fix unclosed tags (e.g., <hello) returning empty string in escape and recursiveEscape modes. Fixes #​706.
  Thanks to Byeong Hyeon for the fix.

v2.17.0

Compare Source

• Add preserveEscapedAttributes, allowing attributes on escaped disallowed tags to be retained. Thanks to Ben Elliot for this new option.

v2.16.0

Compare Source

• Add onOpenTag and onCloseTag events to enable advanced filtering to hook into the parser. Thanks to Rimvydas Naktinis.

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Quality Gate passed

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