CVE-2026-41591

What it is

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.

At a glance

Exploitability

Can be exploited over the network with a low-privilege account. Limited direct impact.

Exploit odds

0.2% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2026-05-08 16:16 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-08-26 19:16 UTC Last updatedMost recent change to the record

Details

Published

2026-05-08 16:16 UTC

Last modified

2026-08-26 19:16 UTC

Exploit probability

0.2% · EPSS, next 30 days

Weakness

CWE-79 · Cross-site scripting

Record status

Analyzed

Affected

• Openjsf Marko < 5.38.36
• Openjsf marko\/runtime-tags < 6.0.164

Attack profile CVSS 3.1 · 6.4

Attack vector

Network

Complexity

Low

Privileges needed

Low

User interaction

None

Scope

Changed

Confidentiality

Low

Integrity

Low

Availability

None