CVE-2026-66010
MEDIUMDOMPurify before 3.4.12 Hook Bypass via CUSTOM_ELEMENT_HANDLING
Title source: cnaDescription
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 (2)
Core 2
Core References
Vendor Advisory vendor-advisory
GitHub Security Advisory (GHSA-c2j3-45gr-mqc4)
https://github.com/cure53/DOMPurify/security/advisories/GHSA-c2j3-45gr-mqc4
Third Party Advisory third-party-advisory
VulnCheck Advisory: DOMPurify before 3.4.12 Hook Bypass via CUSTOM_ELEMENT_HANDLING
https://www.vulncheck.com/advisories/dompurify-before-hook-bypass-via-custom-element-handling
Scores
CVSS v3
6.1
EPSS
0.0017
EPSS Percentile
6.4%
Attack Vector
NETWORK
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
CISA SSVC
Vulnrichment
Exploitation
poc
Automatable
no
Technical Impact
partial
Details
CWE
CWE-79
Status
published
Products (2)
cure53/DOMPurify
< 3.4.12
cure53/DOMPurify
3.4.12
Published
Jul 24, 2026
Tracked Since
Jul 24, 2026