medium6.1
CVE-2026-41240
DOMPurify: FORBID_TAGS bypassed by function-based ADD_TAGS predicate (asymmetry with FORBID_ATTR fix)
Impact
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.
Affected packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| npm | dompurify | < 3.4.0 | 3.4.0 |
Affected products
| Vendor | Product | Affected versions |
|---|---|---|
| Cure53 | Dompurify | before 3.4.0 |
Weakness classification
References
- NVD record
- CVE.org record
- GitHub advisory
- https://github.com/advisories/GHSA-h7mw-gpvr-xq4m
- https://github.com/cure53/DOMPurify/security/advisories/GHSA-h7mw-gpvr-xq4m
- https://github.com/cure53/DOMPurify/releases/tag/3.4.0
- https://nvd.nist.gov/vuln/detail/CVE-2026-41240
- https://github.com/cure53/DOMPurify/commit/c361baa18dbdcb3344a41110f4c48ad85bf48f80