{"id":"CVE-2026-41591","summary":"Marko: XSS via case-insensitive script/style closing tag bypass in runtime HTML escaping","details":"Marko is a declarative, HTML-based language for building web apps. Prior to marko version 5.38.36 and prior to @marko/runtime-tags 6.0.164, when dynamic text is interpolated into a \u003cscript\u003e or \u003cstyle\u003e tag the Marko runtime failed to prevent tag breakout when the closing tag used non-lowercase casing. An attacker able to place input inside a \u003cscript\u003e or \u003cstyle\u003e block could break out of the tag with \u003c/SCRIPT\u003e, \u003c/Style\u003e, etc. and inject arbitrary HTML/JavaScript, resulting in cross-site scripting. This issue has been patched in marko version 5.38.36 and @marko/runtime-tags 6.0.164.","aliases":["GHSA-x9fj-57fh-c8wq"],"modified":"2026-07-15T01:49:00.143339938Z","published":"2026-05-08T15:22:50.990Z","database_specific":{"cwe_ids":["CWE-79"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/41xxx/CVE-2026-41591.json","cna_assigner":"GitHub_M"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/41xxx/CVE-2026-41591.json"},{"type":"ADVISORY","url":"https://github.com/marko-js/marko/security/advisories/GHSA-x9fj-57fh-c8wq"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-41591"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/marko-js/marko","events":[{"introduced":"8e7eb507dc1b2e6da1f3221a2363c4e898891b1c"},{"last_affected":"8e7eb507dc1b2e6da1f3221a2363c4e898891b1c"}],"database_specific":{"source":"AFFECTED_FIELD","extracted_events":[{"introduced":"marko \u003c 5.38.36"},{"last_affected":"marko \u003c 5.38.36"},{"introduced":"@marko/runtime-tags \u003c 6.0.164"},{"last_affected":"@marko/runtime-tags \u003c 6.0.164"}]}}],"versions":["marko \u003c 5.38.36","marko@5.38.36","@marko/runtime-tags@6.0.164"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-41591.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N"}]}