CVE-2026-65902 DOMPurify before 3.4.7 Hook Mutation Pollution via allowedTags
DOMPurify allows persistent allow-list pollution via hooks, enabling XSS by bypassing sanitization for subsequent calls.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-65902?
CVE-2026-65902 is a medium-severity cross-site scripting vulnerability in cure53 DOMPurify, published on 23 Jul 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official description
DOMPurify before 3.4.7 passes direct references to the module-level DEFAULT_ALLOWED_TAGS and DEFAULT_ALLOWED_ATTR sets to the uponSanitizeElement and uponSanitizeAttribute hooks via data.allowedTags / data.allowedAttributes when sanitize is called without an explicit cfg.ALLOWED_TAGS / cfg.ALLOWED_ATTR array. A hook that mutates these fields permanently widens the default allow-lists for the lifetime of the DOMPurify instance, so all subsequent default-config sanitize calls inherit the widened defaults and attacker payloads using the poisoned tag/attribute name survive sanitization. removeAllHooks(), clearConfig(), and passing a fresh cfg do not recover the state; only constructing a new DOMPurify instance does.
Weakness: CWE-501
Which versions are affected by CVE-2026-65902?
2 open source packages ship an affected version, including dompurify. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
dompurify npm | All versions | 3.4.7 |
dompurify npm | All versions | 3.4.7 |
Products include Cure53 Dompurify.
How do I fix CVE-2026-65902?
Upgrade dompurify to 3.4.7 or later.
Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.
Is CVE-2026-65902 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-65902 exists.
Other vulnerabilities in cure53 DOMPurify
- CVE-2024-47875 DOMPurify nesting-based mXSS
- CVE-2024-48910 DOMPurify vulnerable to tampering by prototype polution
- CVE-2026-47423 DOMPurify XSS via `selectedcontent` re-clone
- CVE-2024-45801 Tampering by prototype polution in DOMPurify
- CVE-2026-49978 DOMPurify IN_PLACE Sanitization Bypass via Attached Shadow Root Inside <template>.content
Sources
Also known as DEBIAN-CVE-2026-65902, ECHO-cf5d-0476-1b92, GHSA-76mc-f452-cxcm, MINI-3jw8-r6qm-fvhj, MINI-4h9c-jvjc-pr38, MINI-5j9c-vhf8-pm8h and 17 more.