cure53 DOMPurify up to 3.4.3 _isNode cross site scripting

Summaryinfo

A vulnerability has been found in cure53 DOMPurify up to 3.4.3 and classified as problematic. This issue affects the function _isNode. The manipulation leads to cross site scripting. This vulnerability is referenced as CVE-2026-65904. Remote exploitation of the attack is possible. No exploit is available.

Detailsinfo

A vulnerability was found in cure53 DOMPurify up to 3.4.3 and classified as problematic. This issue affects the function _isNode. The manipulation with an unknown input leads to a cross site scripting vulnerability. Using CWE to declare the problem leads to CWE-79. The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. Impacted is integrity. The summary by CVE is:

DOMPurify through 3.3.3 fails to sanitize DOM elements passed via IN_PLACE mode when the element originates from a different window/realm (e.g., an iframe's contentDocument). A cross-realm instanceof check in the private _isNode() function returns false for foreign-realm nodes, causing DOMPurify to stringify the element (yielding '[object HTMLDivElement]'), silently reset IN_PLACE to false, and return the unsanitized element unchanged with any XSS payloads intact. The vendor considers this an edge case outside DOMPurify's threat model and, at time of publication, no fix was planned.

It is possible to read the advisory at github.com. The identification of this vulnerability is CVE-2026-65904 since 07/23/2026. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. It demands that the victim is doing some kind of user interaction. Technical details of the vulnerability are known, but there is no available exploit. The attack technique deployed by this issue is T1059.007 according to MITRE ATT&CK.

Upgrading to version 3.4.4 eliminates this vulnerability.

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Productinfo

Vendor

• cure53

Name

• DOMPurify

Version

• 3.4.0
• 3.4.1
• 3.4.2
• 3.4.3

Website

• Product: https://github.com/cure53/DOMPurify/

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