CVE-2026-41238
DOMPurify: Prototype Pollution to XSS Bypass via CUSTOM_ELEMENT_HANDLING Fallback
- Published
- Updated
- Reserved
- Assigned by
- GitHub_M
Description
DOMPurify is a DOM-only cross-site scripting sanitizer for HTML, MathML, and SVG. Versions 3.0.1 through 3.3.3 are vulnerable to a prototype pollution-based XSS bypass. When an application uses `DOMPurify.sanitize()` with the default configuration (no `CUSTOM_ELEMENT_HANDLING` option), a prior prototype pollution gadget can inject permissive `tagNameCheck` and `attributeNameCheck` regex values into `Object.prototype`, causing DOMPurify to allow arbitrary custom elements with arbitrary attributes — including event handlers — through sanitization. Version 3.4.0 fixes the issue.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| GitHub_MCNA (assigner) | 3.1 | Medium6.9 | CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:L/A:N |
| NVDNVD · Deferred | 3.1 | Medium6.9 | CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:L/A:N |
- EPSS (exploitation in 30 days)
- 0.27% · top 81% of all CVEs (6 Nov 2026)
- CISA SSVC
- Exploitation: poc · Automatable: no · Technical impact: partial
The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 6.9.
Weakness
Affected products
Affected packages
From reviewed advisories of the GitHub Advisory Database.
- npmdompurifyGHSA-v9jr-rg53-9pgp (opens in a new tab)
References (2)
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisory GHSA-v9jr-rg53-9pgp (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://trackcve.app/cve/CVE-2026-41238)Record last updated .