{"id":"CVE-2026-41591","state":"PUBLISHED","title":"Marko: XSS via case-insensitive script/style closing tag bypass in runtime HTML escaping","description":"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 <script> or <style> 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 <script> or <style> block could break out of the tag with </SCRIPT>, </Style>, 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.","publishedAt":"2026-05-08T15:22:50.990Z","updatedAt":"2026-05-08T21:26:58.356Z","severity":{"score":6.4,"label":"Medium","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N","source":"GitHub_M"},"assigner":"GitHub_M","products":["marko-js marko"],"affected":[{"vendor":"marko-js","product":"marko","versions":[{"version":"marko < 5.38.36","status":"affected"},{"version":"@marko/runtime-tags < 6.0.164","status":"affected"}]}],"references":["https://github.com/marko-js/marko/security/advisories/GHSA-x9fj-57fh-c8wq"],"weaknesses":["CWE-79"],"ingestedAt":"2026-10-29T20:11:57.932Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/41xxx/CVE-2026-41591.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-41591","state":"PUBLISHED","datePublished":"2026-05-08T15:22:50.990Z","dateUpdated":"2026-05-08T21:26:58.356Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-04-21T14:15:21.960Z"},"containers":{"cna":{"title":"Marko: XSS via case-insensitive script/style closing tag bypass in runtime HTML escaping","descriptions":[{"lang":"en","value":"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 <script> or <style> 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 <script> or <style> block could break out of the tag with </SCRIPT>, </Style>, 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."}],"affected":[{"vendor":"marko-js","product":"marko","versions":[{"version":"marko < 5.38.36","status":"affected"},{"version":"@marko/runtime-tags < 6.0.164","status":"affected"}]}],"references":[{"url":"https://github.com/marko-js/marko/security/advisories/GHSA-x9fj-57fh-c8wq","name":"https://github.com/marko-js/marko/security/advisories/GHSA-x9fj-57fh-c8wq","tags":["x_refsource_CONFIRM"]}],"metrics":[{"cvssV3_1":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"NONE","baseScore":6.4,"baseSeverity":"MEDIUM","confidentialityImpact":"LOW","integrityImpact":"LOW","privilegesRequired":"LOW","scope":"CHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N","version":"3.1"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-79","lang":"en","description":"CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-05-08T15:22:50.990Z"},"source":{"advisory":"GHSA-x9fj-57fh-c8wq","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","references":[{"url":"https://github.com/marko-js/marko/security/advisories/GHSA-x9fj-57fh-c8wq","tags":["exploit"]}],"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-05-08T17:08:43.350843Z","id":"CVE-2026-41591","options":[{"Exploitation":"poc"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-05-08T21:26:58.356Z"}}]}}}