CVE-2026-41240 DOMPurify: FORBID_TAGS bypassed by function-based ADD_TAGS predicate (asymmetry with FORBID_ATTR fix)
DOMPurify fails to enforce FORBID_TAGS when function-based ADD_TAGS is used, allowing XSS via forbidden elements.
- 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-2026-41240?
CVE-2026-41240 is a medium-severity cross-site scripting vulnerability in cure53 DOMPurify, published on 23 Apr 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 is a DOM-only cross-site scripting sanitizer for HTML, MathML, and SVG. Versions prior to 3.4.0 have an inconsistency between FORBID_TAGS and FORBID_ATTR handling when function-based ADD_TAGS is used. Commit c361baa added an early exit for FORBID_ATTR at line 1214. The same fix was not applied to FORBID_TAGS. At line 1118-1123, when EXTRA_ELEMENT_HANDLING.tagCheck returns true, the short-circuit evaluation skips the FORBID_TAGS check entirely. This allows forbidden elements to survive sanitization with their attributes intact. Version 3.4.0 patches the issue.
Which versions are affected by CVE-2026-41240?
2 open source packages ship an affected version, including dompurify. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
dompurify npm | All versions | 3.4.0 |
dompurify npm | All versions | 3.4.0 |
Linux distribution packages (1)
argocd-cli openSUSE:Tumbleweed | All versions | 3.4.3-1.1 |
Products include Cure53 Dompurify.
How do I fix CVE-2026-41240?
Upgrade dompurify to 3.4.0 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-2026-41240 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-41240 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 CLEANSTART-2026-PO95463, CLEANSTART-2026-SE92910, DEBIAN-CVE-2026-41240, ECHO-a5a3-4e39-a94b, GHSA-h7mw-gpvr-xq4m, MINI-42pm-x8wv-jhvm and 13 more.