{"id":"CVE-2026-6827","state":"PUBLISHED","title":"justhtml before 1.17.0 Multiple Cross-Site Scripting Vulnerabilities","description":"justhtml before 1.17.0 contains multiple security issues in sanitization, serialization, and programmatic DOM handling. When custom policies preserve foreign namespaces (SVG/MathML), dangerous content such as HTML integration points (SVG <foreignObject>, MathML <annotation-xml encoding=\"text/html\">) and mutation-XSS parser-differential payloads could survive sanitization and become active HTML after reparse; SVG filter=\"url(...)\" and preserved <style> could leave resource-loading CSS (@import, background-image:url()). Programmatic script/style/Comment nodes could serialize into active markup. Additional hardening fixes address sanitize-pipeline cache mutation and DOM parent/child cycles that could cause infinite loops. Most issues affect advanced or custom configurations rather than the default JustHTML(..., sanitize=True) safe path.","publishedAt":"2026-08-23T13:34:11.236Z","updatedAt":"2026-08-29T11:47:34.707Z","severity":{"score":5.1,"label":"Medium","version":"4.0","vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N","source":"VulnCheck"},"assigner":"VulnCheck","products":["EmilStenstrom justhtml"],"affected":[{"vendor":"EmilStenstrom","product":"justhtml","packageURL":"pkg:pypi/justhtml","defaultStatus":"unaffected","versions":[{"version":"0","status":"affected","lessThan":"1.17.0","versionType":"semver"},{"version":"1.17.0","status":"unaffected","versionType":"semver"}]}],"references":["https://github.com/EmilStenstrom/justhtml/security/advisories/GHSA-vrx2-77f2-ww34","https://www.vulncheck.com/advisories/justhtml-before-multiple-cross-site-scripting-vulnerabilities"],"weaknesses":["CWE-79"],"ingestedAt":"2026-10-29T20:12:49.727Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/6xxx/CVE-2026-6827.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-6827","state":"PUBLISHED","datePublished":"2026-08-23T13:34:11.236Z","dateUpdated":"2026-08-29T11:47:34.707Z","assignerShortName":"VulnCheck","assignerOrgId":"83251b91-4cc7-4094-a5c7-464a1b83ea10","dateReserved":"2026-04-21T20:44:33.519Z"},"containers":{"cna":{"title":"justhtml before 1.17.0 Multiple Cross-Site Scripting Vulnerabilities","descriptions":[{"lang":"en","value":"justhtml before 1.17.0 contains multiple security issues in sanitization, serialization, and programmatic DOM handling. 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