CVE-2026-41238

MEDIUM

DOMPurify: Prototype Pollution to XSS Bypass via CUSTOM_ELEMENT_HANDLING Fallback

Title source: cna
STIX 2.1

Description

DOMPurify is a DOM-only cross-site scripting sanitizer for HTML, MathML, and SVG. Versions 3.0.1 through 3.3.3 are vulnerable to a prototype pollution-based XSS bypass. When an application uses `DOMPurify.sanitize()` with the default configuration (no `CUSTOM_ELEMENT_HANDLING` option), a prior prototype pollution gadget can inject permissive `tagNameCheck` and `attributeNameCheck` regex values into `Object.prototype`, causing DOMPurify to allow arbitrary custom elements with arbitrary attributes — including event handlers — through sanitization. Version 3.4.0 fixes the issue.

References (2)

Core 2
Core References
X_Refsource_Misc x_refsource_misc
https://github.com/cure53/DOMPurify/releases/tag/3.4.0

Scores

CVSS v3 6.9
EPSS 0.0021
EPSS Percentile 10.5%
Attack Vector NETWORK
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:L/A:N

CISA SSVC

Vulnrichment
Exploitation poc
Automatable no
Technical Impact partial

Details

CWE
CWE-1321 CWE-79
Status published
Products (2)
cure53/DOMPurify >= 3.0.1, < 3.4.0
npm/dompurify 3.0.1 - 3.4.0npm
Published Apr 23, 2026
Tracked Since Apr 23, 2026