What is CVE-2026-65904?

CVE-2026-65904 is a medium-severity vulnerability in Cure53 Dompurify, classified under Improper Check for Unusual or Exceptional Conditions. CVSS score: 4.7/10. Published 2026-07-23.

How severe is CVE-2026-65904?

Medium severity. CVSS v3 base score is 4.7 out of 10.

Vulnerability in Cure53 Dompurify

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.

EPSS: 0.002 (10.6th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 4.7 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:L/A:N.

Affected products

Cure53 Dompurify — versions 0, 3.4.4

Weakness classification (CWE)

CWE-754 — Improper Check for Unusual or Exceptional Conditions

References

disclosure@vulncheck.com (Exploit, vendor-advisory, Third Party Advisory)
disclosure@vulncheck.com (Third Party Advisory, third-party-advisory)

Frequently asked questions

What is CVE-2026-65904?: CVE-2026-65904 is a medium-severity vulnerability in Cure53 Dompurify, classified under Improper Check for Unusual or Exceptional Conditions. CVSS score: 4.7/10. Published 2026-07-23.
How severe is CVE-2026-65904?: Medium severity. CVSS v3 base score is 4.7 out of 10.