CVE-2026-65904

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.

CVSS 4.0

2.3CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N

CVSS 3.1

4.7CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:L/A:N

EPSS

0.3% chance of exploitation in the next 30 days; higher than 18% of CVEs (scores of 2026-10-25)

CWE

CWE-754

Published

2026-07-23

Modified

2026-10-24

Record from

the NVD, synced 2026-10-24

Affected

• cure53:dompurify

References

• https://github.com/cure53/DOMPurify/security/advisories/GHSA-4w3q-35jp-p934
• https://www.vulncheck.com/advisories/dompurify-before-cross-site-scripting-via-in-place-mode
• https://github.com/cure53/DOMPurify/security/advisories/GHSA-4w3q-35jp-p934

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