{"id":"CVE-2026-41240","aliases":["GHSA-h7mw-gpvr-xq4m"],"url":"https://o3.security/vulnerability/CVE-2026-41240","summary":"DOMPurify: FORBID_TAGS bypassed by function-based ADD_TAGS predicate (asymmetry with FORBID_ATTR fix)","details":"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.","published":"2026-04-23T14:54:32.426Z","modified":"2026-08-12T03:51:48.387563850Z","cvss":null,"epss":{"score":0.00313,"percentile":0.23829,"asOf":"2026-08-12"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"npm","name":"dompurify","fixedVersion":"3.4.0"}],"fix":{"url":"https://github.com/cure53/DOMPurify/commit/c361baa18dbdcb3344a41110f4c48ad85bf48f80","label":"cure53/DOMPurify@c361baa"},"references":[{"type":"WEB","url":"https://github.com/cure53/DOMPurify/releases/tag/3.4.0"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/41xxx/CVE-2026-41240.json"},{"type":"ADVISORY","url":"https://github.com/cure53/DOMPurify/security/advisories/GHSA-h7mw-gpvr-xq4m"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-41240"},{"type":"FIX","url":"https://github.com/cure53/DOMPurify/commit/c361baa18dbdcb3344a41110f4c48ad85bf48f80"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-12T03:51:48.387563850Z"}}