Vulnerability Description
In DOMPurify through 3.3.3, function predicates supplied via ADD_ATTR or ADD_TAGS to DOMPurify.sanitize() persist in internal state (EXTRA_ELEMENT_HANDLING) across subsequent sanitize() calls on the same instance. If a later call on the same instance provides ADD_ATTR or ADD_TAGS as an array rather than a function, the previously set function handler is neither cleared nor overwritten, so it continues to approve attacker-controlled attributes or tags. This can allow dangerous event-handler attributes or forbidden tags (bypassing FORBID_TAGS) to survive sanitization, resulting in cross-site scripting. The vendor (Cure53) considers this an edge case outside DOMPurify's threat model; the referenced advisory lists 3.4.0 as the patched version.
CVSS Score
MEDIUM
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Cure53 | Dompurify | < 3.4.0 |
Related Weaknesses (CWE)
References
- https://github.com/cure53/DOMPurify/security/advisories/GHSA-9p3w-6h5p-cv75ExploitThird Party Advisory
- https://www.vulncheck.com/advisories/dompurify-before-xss-via-add-attr-add-tags-Third Party Advisory
FAQ
What is CVE-2026-65911?
CVE-2026-65911 is a vulnerability with a CVSS score of 6.1 (MEDIUM). In DOMPurify through 3.3.3, function predicates supplied via ADD_ATTR or ADD_TAGS to DOMPurify.sanitize() persist in internal state (EXTRA_ELEMENT_HANDLING) across subsequent sanitize() calls on the s...
How severe is CVE-2026-65911?
CVE-2026-65911 has been rated MEDIUM with a CVSS base score of 6.1/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-65911?
Check the references section above for vendor advisories and patch information. Affected products include: Cure53 Dompurify.