DOMPurify: SMIL attributeName=href guard is skipped when PARSER_MEDIA_TYPE is application/xhtml+xml

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

not scored

EPSS

• CVE-2026-116802: 0.22% estimated exploitation activity in the next 30 days; percentile 12.22 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary DOMPurify drops `attributeName` attributes whose value contains `href`, so an allowed ` ` or ` ` can't rewrite a link's href after sanitizing. The check compares the attribute name after `transformCaseFunc`, and that function doesn't lowercase in XHTML mode. In XHTML the attribute is spelled `attributeName`, so the comparison with `"attributename"` never matches and the guard does nothing. An app that uses `PARSER_MEDIA_TYPE: 'application/xhtml+xml'` and allows `animate` and `attributeName` will keep ` `. Clicking the parent link then runs the script. This needs a non-default config, so going by SECURITY.md, this is a hardening bug rather than a bypass of the default config.

Details In `_sanitizeAttributes` (dist/purify.js line 2216 in 3.4.16): ```js const lcName = transformCaseFunc(name); ... if (lcName === "attributename" && stringMatch(value, "href")) { _removeAttribute(name, currentNode, attr); continue; } ``` `transformCaseFunc` is `stringToLowerCase` for…

Published by the source

22 Oct 2026, 16:24 UTC

Last modified by the source

27 Oct 2026, 10:56 UTC

Source last checked

28 Oct 2026, 06:00 UTC

1. Revision 4 · amended · 28 Oct 2026

   Amended from osv record GHSA-c6gr-qvv4-5v3f

2. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-c6gr-qvv4-5v3f

3. Revision 2 · amended · 24 Oct 2026

   Amended from osv record GHSA-c6gr-qvv4-5v3f

4. Revision 1 · created · 23 Oct 2026

   Published from ghsa record GHSA-c6gr-qvv4-5v3f

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# Patch Next advisory brief: CVE-2026-116802

Advisory: DOMPurify: SMIL attributeName=href guard is skipped when PARSER_MEDIA_TYPE is application/xhtml+xml
IDs: CVE-2026-116802, GHSA-c6gr-qvv4-5v3f
Record: https://patchnext.com/advisories/ghsa-c6gr-qvv4-5v3f (revision 4, source checked 28 Oct 2026, 06:00 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Unrated
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: dompurify 3.4.17. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm dompurify: affected < 3.4.17; fixed in 3.4.17

## Suggested inspection (read-only)
- `npm ls dompurify --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on dompurify.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-c6gr-qvv4-5v3f (GitHub-reviewed advisory GHSA-c6gr-qvv4-5v3f lists affected ranges: npm dompurify >=0 <=3.4.16)
- Verified: https://osv.dev/vulnerability/GHSA-c6gr-qvv4-5v3f (OSV record GHSA-c6gr-qvv4-5v3f lists affected ranges: npm dompurify >=0 <3.4.17 (fixed))

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