CVE-2026-65904

Medium

Description

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.

SeverityMedium

CVSS4.7

Exploit probability—

ProductCure53 Dompurify

PublishedJul 23, 2026

First seenJul 23, 2026

Weakness typeCWE-754CWE-754

How to fix

Update

cure53 dompurify3.4.4 or later

Vendor advisories

github.com/cure53/DOMPurify/security/advisories/GHSA-4w3q-35jp-p934

Affected products

Product	Affected versions	Fixed in
cure53 dompurify	v < 3.4.4	3.4.4

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