Protection Mechanism Failure in DOMPurify - CVE-2026-65899
Published: June 12, 2026 / Updated: September 14, 2026
Vulnerability identifier: #VU134420
CSH Severity: Medium
CVSS v4: 7.6 [CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-65899
CWE-ID: CWE-693
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote user to execute arbitrary script in the context of a Trusted Types sink.
The vulnerability exists due to a protection mechanism failure in the Trusted Types policy handling in DOMPurify when reusing a DOMPurify instance across trust boundaries after calling clearConfig() and requesting RETURN_TRUSTED_TYPE. A remote user can influence a previously supplied trusted types policy on the reused instance to execute arbitrary script in the context of a Trusted Types sink.
Exploitation requires a shared DOMPurify instance, a previously retained unsafe or less-trusted policy, and a later sanitize call that requests RETURN_TRUSTED_TYPE.
Affected software
DOMPurify
How to mitigate CVE-2026-65899
Install security update from vendor's website.
DOMPurify - update to 3.4.9