CVE-2026-66010

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.

SeverityMedium

CVSS6.1

Exploit probability—

ProductCure53 Dompurify

PublishedJul 24, 2026

First seenJul 24, 2026

Weakness typeCWE-79Cross-site scripting (XSS)

How to fix

Update

cure53 dompurify3.4.12 or later
dompurify3.4.12 or later

Vendor advisories

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

Affected products

Product	Affected versions	Fixed in
cure53 dompurify	v < 3.4.12	3.4.12
dompurifynpm	v < 3.4.12	3.4.12

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