CVE-2026-49458

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

State: Published
Severity: 6.1 Medium
Published: Jul 14, 2026
Updated: Jul 15, 2026
Reserved: May 30, 2026

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.

Scores

CVSS	Score	Vector	Source
3.1	6.1 Medium	CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N	GitHub_M

Weaknesses

CWE-79 Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
CWE-501 Trust Boundary Violation
CWE-693 Protection Mechanism Failure

Affected Products

Product	Versions
DOMPurifycure53	< 3.4.6Affected

References

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