CVE-2026-66010

MEDIUM6.1

DOMPurify before 3.4.12 Hook Bypass via CUSTOM_ELEMENT_HANDLING

Published Jul 24, 2026

Modified 1 months ago

Details

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.

References

ADVISORY

https://github.com/cure53/DOMPurify/security/advisories/GHSA-c2j3-45gr-mqc4

ADVISORY

https://www.cve.org/CVERecord?id=CVE-2026-66010

ADVISORY

https://www.vulncheck.com/advisories/dompurify-before-hook-bypass-via-custom-element-handling

CVSS Analysis

CVSS v4.0

5.1

Exploitability

Attack Vector