{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "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"
              }
            ],
            "source": "AFFECTED_FIELD"
          },
          "events": [
            {
              "introduced": "8e7eb507dc1b2e6da1f3221a2363c4e898891b1c"
            },
            {
              "last_affected": "8e7eb507dc1b2e6da1f3221a2363c4e898891b1c"
            }
          ],
          "repo": "https://github.com/marko-js/marko",
          "type": "GIT"
        }
      ],
      "versions": [
        "marko \u003c 5.38.36"
      ]
    }
  ],
  "aliases": [
    "GHSA-x9fj-57fh-c8wq"
  ],
  "database_specific": {
    "cna_assigner": "GitHub_M",
    "cwe_ids": [
      "CWE-79"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/41xxx/CVE-2026-41591.json"
  },
  "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.",
  "id": "CVE-2026-41591",
  "modified": "2026-07-15T01:49:00.143339938Z",
  "published": "2026-05-08T15:22:50.990Z",
  "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"
    }
  ],
  "schema_version": "1.8.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Marko: XSS via case-insensitive script/style closing tag bypass in runtime HTML escaping"
}