CVE-2026-41240

Medium

Description

DOMPurify is a DOM-only cross-site scripting sanitizer for HTML, MathML, and SVG. Versions prior to 3.4.0 have an inconsistency between FORBID_TAGS and FORBID_ATTR handling when function-based ADD_TAGS is used. Commit c361baa added an early exit for FORBID_ATTR at line 1214. The same fix was not applied to FORBID_TAGS. At line 1118-1123, when EXTRA_ELEMENT_HANDLING.tagCheck returns true, the short-circuit evaluation skips the FORBID_TAGS check entirely. This allows forbidden elements to survive sanitization with their attributes intact. Version 3.4.0 patches the issue.

SeverityMedium

CVSS6.1

Exploit probability—

ProductCure53 Dompurify

PublishedApr 23, 2026

First seenApr 23, 2026

Weakness typeCWE-183CWE-183 CWE-79Cross-site scripting (XSS)

How to fix

Update

cure53 dompurify3.4.0 or later
dompurify3.4.0 or later

Affected products

Product	Affected versions	Fixed in
cure53 dompurify	v < 3.4.0	3.4.0
dompurifynpm	v < 3.4.0	3.4.0

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