Marko: XSS via case-insensitive script/style closing tag bypass in runtime HTML escaping_CVE-2026-41591

{
    "lastseen": "",
    "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.",
    "published": "2026-05-08T15:22:50.990Z",
    "modified": "2026-05-08T15:22:50.990Z",
    "type": "cve",
    "title": "Marko: XSS via case-insensitive script/style closing tag bypass in runtime HTML escaping",
    "source": "GitHub_M",
    "references": "https://github.com/marko-js/marko/security/advisories/GHSA-x9fj-57fh-c8wq",
    "id": "CVE-2026-41591",
    "bulletinFamily": "",
    "cwe": [
        "CWE-79"
    ],
    "cvelist": null,
    "sourceData": "marko-js marko marko < 5.38.36\nmarko-js marko @marko/runtime-tags < 6.0.164",
    "sourceHref": "",
    "cvss": {
        "score": 6.4,
        "severity": "MEDIUM",
        "vector": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N",
        "version": "3.1"
    },
    "cvss2": [],
    "cvss3": {
        "version": "",
        "vectorString": "",
        "baseScore": 0,
        "baseSeverity": "",
        "attackVector": "",
        "attackComplexity": "",
        "privilegesRequired": "",
        "userInteraction": "",
        "scope": "",
        "confidentialityImpact": "",
        "integrityImpact": "",
        "availabilityImpact": "",
        "cvssV3": {
            "version": "",
            "vectorString": "",
            "baseScore": 0,
            "baseSeverity": "",
            "attackVector": "",
            "attackComplexity": "",
            "privilegesRequired": "",
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            "confidentialityImpact": "",
            "integrityImpact": "",
            "availabilityImpact": ""
        }
    },
    "href": "",
    "category_name": "CVE",
    "post_link": "",
    "product": "marko",
    "version": "marko < 5.38.36",
    "vendor": "marko-js",
    "ai_description": "",
    "ai_severity": "",
    "ai_vendor": "",
    "ai_product": "",
    "ai_version": "",
    "ai_score": 0
}