CVE-2026-66010 | DOMPurify before 3.4.12 fails to execute afterSanitizeElemen… | CVSS 6.1 MEDIUM

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.

Metadata

CVE ID: CVE-2026-66010
State: PUBLISHED
Assigner: VulnCheck
Reserved: 2026-07-23 19:22 UTC
Published: 2026-07-24 12:07 UTC
Last updated: 2026-07-24 14:14 UTC
Primary CWE: CWE-79
Improper Neutralization of Input During Web Page Generation …
Vendor / Product: cure53 / DOMPurify
Sources: cve.org · NVD

Severity & Metrics

6.1 MEDIUM CVSS 3.1

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

SSVC — CISA Coordinator

Exploitation: PoC
Automatable: no
Tech. Impact: partial

Affected products (1)

Vendor	Product	Platform	Versions
cure53	DOMPurify	—	0 < 3.4.12, 3.4.12

Weakness (CWE)

CWE	Source	Description
CWE-79	cna	Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

CVSS scores (2)

Score	Severity	Version	Source	Vector
6.1	MEDIUM	3.1	cna	CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
5.1	MEDIUM	4.0	cna	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

References (2)

GitHub Security Advisory (GHSA-c2j3-45gr-mqc4) https://github.com/cure53/DOMPurify/security/advisories/GHSA-c2j3-45gr-mqc4
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