{"id":"CVE-2026-66010","title":"DOMPurify before 3.4.12 Hook Bypass via CUSTOM_ELEMENT_HANDLING","summary":"DOMPurify before 3.4.12 fails to execute afterSanitizeElements hook for custom elements allowed via CUSTOM_ELEMENT_HANDLING.tagNameCheck, allowing attributes to bypass application security policies. Attackers can preserve sensitive attri…","severity":"medium","cvss":6.1,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N","cvssSource":"cna","cwe":["CWE-79"],"vendor":"cure53","product":"DOMPurify","affected":["DOMPurify < 3.4.12"],"ssvc":{"exploitation":"poc","automatable":"no","technicalImpact":"partial","timestamp":"2026-07-24T14:13:53.590696Z"},"exploitAvailable":true,"published":"2026-07-24","updated":"2026-09-17","sourceUpdated":"2026-09-17T17:54:37.884Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-66010","references":[{"url":"https://github.com/cure53/DOMPurify/security/advisories/GHSA-c2j3-45gr-mqc4","label":"GitHub Security Advisory (GHSA-c2j3-45gr-mqc4)"},{"url":"https://www.vulncheck.com/advisories/dompurify-before-hook-bypass-via-custom-element-handling","label":"VulnCheck Advisory: DOMPurify before 3.4.12 Hook Bypass via CUSTOM_ELEMENT_HANDLING"}],"tags":["cve.org","exploit-available"],"epss":0.00215,"epssPercentile":0.12186,"ingestedAt":"2026-09-17T18:25:16.054Z","slug":"CVE-2026-66010","body":"## Overview\n\nDOMPurify before 3.4.12 fails to execute afterSanitizeElements hook for custom elements allowed via CUSTOM_ELEMENT_HANDLING.tagNameCheck, allowing attributes to bypass application security policies. Attackers can preserve sensitive attributes on custom elements that later re-inject them into innerHTML sinks, creating second-order XSS gadgets.\n\n## Affected\n\n- `DOMPurify < 3.4.12`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"twilight","depthScore":46,"depthScoreParts":{"impact":33.6,"likelihood":0,"exploitation":12,"ransomware":0},"changes":[]}