CVE-2026-41591
Marko: XSS via case-insensitive script/style closing tag bypass in runtime HTML escaping
CVSS Score
6.4
EPSS Score
0.0%
EPSS Percentile
0th
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.
| CWE | CWE-79 |
| Vendor | marko-js |
| Product | marko |
| Published | May 8, 2026 |
| Last Updated | May 8, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Changed
Confidentiality
Low
Integrity
Low
Availability
None
Affected Versions
marko-js / marko
marko < 5.38.36 @marko/runtime-tags < 6.0.164