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CVE-2026-41591

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

This page contains facts from public vulnerability sources. Check the original advisory before updating.

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.

CVSS 6.4 · Medium · EPSS 0.2% · Fix available

Published
Updated

Stack: node

Affected products and versions

  • marko

    Versions
    • marko < 5.38.36: Affected
    • @marko/runtime-tags < 6.0.164: Affected

    No fix published

  • marko npm

    Affected ranges
    • SEMVER: < 5.38.36

    Update to 5.38.36

  • @marko/runtime-tags npm

    Affected ranges
    • SEMVER: < 6.0.164

    Update to 6.0.164

Original sources

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