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.
History

Fri, 08 May 2026 22:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Fri, 08 May 2026 16:00:00 +0000

Type Values Removed Values Added
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.
Title Marko: XSS via case-insensitive script/style closing tag bypass in runtime HTML escaping
Weaknesses CWE-79
References
Metrics cvssV3_1

{'score': 6.4, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N'}


cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-05-08T21:26:58.356Z

Reserved: 2026-04-21T14:15:21.960Z

Link: CVE-2026-41591

cve-icon Vulnrichment

Updated: 2026-05-08T17:08:56.881Z

cve-icon NVD

Status : Received

Published: 2026-05-08T16:16:11.167

Modified: 2026-05-08T22:16:30.647

Link: CVE-2026-41591

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-05-08T19:15:14Z