CVE-2026-65898 DOMPurify before 3.4.11 Permanent Attribute Allowlist Pollution via setConfig
Attackers can exploit a DOMPurify configuration flaw to permanently pollute attribute allowlists, enabling stored XSS via event handlers.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-65898?
CVE-2026-65898 is a medium-severity cross-site scripting vulnerability in cure53 DOMPurify, published on 23 Jul 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Official description
DOMPurify before 3.4.11 fails to clone the ALLOWED_ATTR allowlist when setConfig() is used with an uponSanitizeAttribute hook, allowing the hook to permanently mutate the shared allowlist. Attackers can register a hook that conditionally allows dangerous attributes like onerror for trusted elements, then submit untrusted content that inherits the polluted allowlist and executes event handlers as stored XSS.
Weakness: CWE-79
Which versions are affected by CVE-2026-65898?
2 open source packages ship an affected version, including dompurify. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
dompurify npm | All versions | 3.4.11 |
dompurify npm | All versions | 3.4.11 |
Products include Cure53 Dompurify.
How do I fix CVE-2026-65898?
Upgrade dompurify to 3.4.11 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-2026-65898 being exploited?
There is no known exploitation of CVE-2026-65898 in the wild and no public exploit code.
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 CLEANSTART-2026-BB38451, CLEANSTART-2026-IE01386, CLSA-2026-1784596280, CLSA-2026-1784596304, CLSA-2026-1784596347, CLSA-2026-1784682972 and 24 more.