DOMPurify before 3.4.12 fails to execute afterSanitizeElements hook for custom elements allowed via CUSTOM_ELEMENT_HANDLING.tagNameCheck, allowing attributes to bypass application security policies. Attackers can preserve sensitive attributes on custom elements that later re-inject them into innerHTML sinks, creating second-order XSS gadgets.
Fix
Patch, vendor advisory and mitigation references on NVD 2
- https://github.com/cure53/DOMPurify/security/advisories/GHSA-c2j3-45gr-mqc4 Exploit, Vendor Advisory
- https://github.com/cure53/DOMPurify/security/advisories/GHSA-c2j3-45gr-mqc4 Exploit, Vendor Advisory
Every line above is quoted from NVD, CISA, Microsoft, the vendor's own advisory or DISA; nothing is generated.
Change history 1
- First seenCVSS 5.1 · cure53NVD modified 2026-10-24 13:10
Affected (CPE criteria) 1
cpe:2.3:a:cure53:dompurify:*:*:*:*:*:*:*:*
References 3
- https://github.com/cure53/DOMPurify/security/advisories/GHSA-c2j3-45gr-mqc4 Exploit, Vendor Advisory
- https://www.vulncheck.com/advisories/dompurify-before-hook-bypass-via-custom-element-handling Third Party Advisory
- https://github.com/cure53/DOMPurify/security/advisories/GHSA-c2j3-45gr-mqc4 Exploit, Vendor Advisory