CVE-2026-66010

DOMPurify before 3.4.12 Hook Bypass via CUSTOM_ELEMENT_HANDLING

Published Jul 24, 2026 CVSS 4.0 · 5.1 Medium EPSS < 1% KEV · Not listed
Description
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Github GHSA Github GHSA GHSA-c2j3-45gr-mqc4 DOMPurify: `CUSTOM_ELEMENT_HANDLING` bypasses `afterSanitizeElements` for allowed custom elements.
History
Type Values Removed Values Added
Description 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.
Title DOMPurify before 3.4.12 Hook Bypass via CUSTOM_ELEMENT_HANDLING
First Time appeared Cure53
Cure53 dompurify
Weaknesses CWE-79
CPEs cpe:2.3:a:cure53:dompurify:*:*:*:*:*:*:*:*
Vendors & Products Cure53
Cure53 dompurify
References
Metrics cvssV3_1

{'score': 6.1, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N'}

cvssV4_0

{'score': 5.1, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N'}

ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
VulnCheck
Published
Updated
Sep 17, 2026, 5:54 PM
Reserved
Jul 23, 2026, 7:22 PM
Status
Analyzed
Published
Jul 24, 2026, 1:18 PM
Modified
Oct 24, 2026, 1:10 PM
Severity
Moderate
Public date
Jul 24, 2026, 12:07 PM