{"id":"CVE-2026-41238","summary":"DOMPurify: Prototype Pollution to XSS Bypass via CUSTOM_ELEMENT_HANDLING Fallback","details":"DOMPurify is a DOM-only cross-site scripting sanitizer for HTML, MathML, and SVG. Versions 3.0.1 through 3.3.3 are vulnerable to a prototype pollution-based XSS bypass. When an application uses `DOMPurify.sanitize()` with the default configuration (no `CUSTOM_ELEMENT_HANDLING` option), a prior prototype pollution gadget can inject permissive `tagNameCheck` and `attributeNameCheck` regex values into `Object.prototype`, causing DOMPurify to allow arbitrary custom elements with arbitrary attributes — including event handlers — through sanitization. Version 3.4.0 fixes the issue.","aliases":["GHSA-v9jr-rg53-9pgp"],"modified":"2026-05-18T06:00:08.761255394Z","published":"2026-04-23T14:43:17.730Z","related":["CGA-p2qv-pg2r-p3rr"],"database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/41xxx/CVE-2026-41238.json","cwe_ids":["CWE-1321","CWE-79"],"cna_assigner":"GitHub_M"},"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-2026-41238.json"},{"type":"ADVISORY","url":"https://github.com/cure53/DOMPurify/security/advisories/GHSA-v9jr-rg53-9pgp"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-41238"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/cure53/dompurify","events":[{"introduced":"e42464f0e06ab5899aae41c89920be9af8b2e826"},{"fixed":"5b16e0b892e82b1779d62b9928b43c4c4ff290b9"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-41238.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:L/A:N"}]}