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.
Published · last modified .
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.
EPSS exploit prediction
EPSS: 0.003 (17.5th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 18th percentile — 17.5% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.003 · newest: 0.003 · change: 0.000
Affected products
- Cure53 Dompurify — versions 0, 3.4.4
Weakness classification (CWE)
References
- github.com/cure53/DOMPurify/security/advisories/GHSA-4w3q-35jp-p934 (Exploit, vendor-advisory, Third Party Advisory)
- www.vulncheck.com/advisories/dompurify-before-cross-site-scripting-via-in-place… (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.