{"id":"CVE-2026-6827","summary":"justhtml before 1.17.0 Multiple Cross-Site Scripting Vulnerabilities","details":"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 \u003cforeignObject\u003e, MathML \u003cannotation-xml encoding=\"text/html\"\u003e) and mutation-XSS parser-differential payloads could survive sanitization and become active HTML after reparse; SVG filter=\"url(...)\" and preserved \u003cstyle\u003e 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.","aliases":["GHSA-vrx2-77f2-ww34"],"modified":"2026-08-25T04:02:39.279744167Z","published":"2026-08-23T13:34:11.236Z","database_specific":{"cna_assigner":"VulnCheck","cwe_ids":["CWE-79"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/6xxx/CVE-2026-6827.json"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/6xxx/CVE-2026-6827.json"},{"type":"ADVISORY","url":"https://github.com/EmilStenstrom/justhtml/security/advisories/GHSA-vrx2-77f2-ww34"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-6827"},{"type":"ADVISORY","url":"https://www.vulncheck.com/advisories/justhtml-before-multiple-cross-site-scripting-vulnerabilities"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/emilstenstrom/justhtml","events":[{"introduced":"0"},{"fixed":"273422f9f8a1b87cb1c13d892b50d3e42141d4e8"}],"database_specific":{"extracted_events":[{"introduced":"0"},{"fixed":"1.16.0"},{"fixed":"1.17.0"}],"source":["AFFECTED_FIELD","DESCRIPTION"]}}],"versions":["v1.15.0","v1.14.0","v1.13.0","v1.12.0","v1.11.0","v1.10.0","v1.9.1","v1.9.0","v1.8.0","v1.7.0","v1.6.0","v1.5.0","v1.4.0","v1.3.0","v1.2.0","v1.1.0","v1.0.0","v0.40.0","v0.39.0","v0.38.0","v0.37.0","v0.36.0","v0.35.0","v0.34.0","v0.33.0","v0.32.0","v0.31.0","v0.30.0","v0.29.0","v0.28.0","v0.27.0","v0.26.0","v0.25.0","v0.24.0","v0.23.0","v0.22.0","v0.21.0","v0.20.0","v0.19.0","v0.18.0","v0.17.0","v0.16.0","v0.15.0","v0.14.0","v0.13.1","v0.13.0","v0.12.0","v0.11.0","v0.10.0","v0.9.0","v0.8.0","v0.7.0","v0.6.0","v0.5.2","v0.5.1","v0.5.0","v0.4.0","v0.3.0","v0.2.0","v0.1.0"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-6827.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V4","score":"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"}]}