{"id":"CVE-2026-5389","summary":"justhtml before 1.13.0 XSS via code fence breakout","details":"justhtml versions before 1.13.0 contain a cross-site scripting vulnerability in the to_markdown() function when serializing attacker-controlled pre content. Attackers can place backticks inside sanitized pre elements to break out of fixed-length code fences, allowing raw HTML to execute when the generated Markdown is rendered by CommonMark or GFM-style renderers.","aliases":["GHSA-5vp3-3cg6-2rq3"],"modified":"2026-08-28T11:30:19.260762016Z","published":"2026-08-23T13:34:09.865Z","database_specific":{"cwe_ids":["CWE-80"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/5xxx/CVE-2026-5389.json","cna_assigner":"VulnCheck"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/5xxx/CVE-2026-5389.json"},{"type":"ADVISORY","url":"https://github.com/EmilStenstrom/justhtml/security/advisories/GHSA-5vp3-3cg6-2rq3"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-5389"},{"type":"ADVISORY","url":"https://www.vulncheck.com/advisories/justhtml-before-xss-via-code-fence-breakout"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/emilstenstrom/justhtml","events":[{"introduced":"0"},{"fixed":"044fb58726f0b1d013276d41b3e54aa6dfd9ab4b"}],"database_specific":{"extracted_events":[{"introduced":"0"},{"fixed":"1.13.0"}],"source":["AFFECTED_FIELD","DESCRIPTION"]}}],"versions":["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-2026-5389.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"}]}