CVE-2026-41238: CURE53 Dompurify

Medium severity, CVSS 6.9. EPSS: 0.3% chance of exploitation in the next 30 days.

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.

Affected products

• CURE53 Dompurify: from 3.0.1, before 3.4.0 (fixed in 3.4.0)

Published 2026-04-23. Last modified 2026-06-17.