What’s Vulnerable › Vulnerabilities

CVE-2026-49458: DOMPurify: Cross-realm IN_PLACE sanitization leaves executable markup intact via realm-bound `instanceof` checks

• Severity: medium (CVSS 6.1 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2026-07-14 · updated 2026-10-24
• Weakness: CWE-79

Description

DOMPurify is a DOM-only cross-site scripting sanitizer for HTML, MathML, and SVG. Prior to 3.4.6, DOMPurify.sanitize(node, { IN_PLACE: true }) accepted same-origin foreign-realm DOM nodes while follow-on checks used parent-realm constructors, causing instanceof checks for forms, named node maps, document fragments, and elements to fail and skip clobber, template-content, and shadow-DOM sanitization branches so executable markup could survive. This issue is fixed in version 3.4.6.

Affected products

• cure53 DOMPurify: before 3.4.6 — fixed in 3.4.6

How to fix

Upgrade to a fixed version: cure53 DOMPurify 3.4.6. Check the vendor advisory for mitigations.

References

• https://github.com/cure53/DOMPurify/commit/bb7739e5bccec7e1ab3dae3f3e42d02db3acaaae
• https://github.com/cure53/DOMPurify/releases/tag/3.4.6
• https://github.com/cure53/DOMPurify/security/advisories/GHSA-hpcv-96wg-7vj8
• https://github.com/cure53/DOMPurify/security/advisories/GHSA-hpcv-96wg-7vj8

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