Bug 2561479 (CVE-2026-116804)

Summary: CVE-2026-116804 dompurify: DOMPurify: Cross-site scripting via sanitization bypass in attached shadow roots
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
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Priority: medium    
Version: unspecifiedKeywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in DOMPurify. When configured to sanitize content for template engines, DOMPurify fails to properly scrub template expressions within attached shadow roots. A remote attacker can exploit this flaw by supplying crafted markup with expressions split across disallowed elements, which recombine after the invalid tags are removed. When the application subsequently evaluates the sanitized content in a downstream template engine, this can lead to cross-site scripting (XSS) or template injection.
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Description OSIDB Bzimport 2026-10-26 23:22:16 UTC
DOMPurify from 3.4.4 before 3.4.17 contains a SAFE_FOR_TEMPLATES bypass that lets attackers preserve template expressions in attached shadow roots when using RETURN_DOM, RETURN_DOM_FRAGMENT, or IN_PLACE modes. Attackers can split expressions across text nodes separated by disallowed elements, which merge after removal and are evaluated by downstream template engines for cross-site scripting.