CVE-2026-41591
MediumCVSS 6.4Exploitation Probability (EPSS)
Low risk13th percentile - higher than 13% of all known CVEs
Summary
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.
Risk Assessment
The risk includes the possibility of injecting malicious scripts, which could lead to user data theft, session hijacking, or other XSS attacks.
Recommendation
Upgrade Marko to version 5.38.36 or later and @marko/runtime-tags to 6.0.164 or later.
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Original NVD description (English source)
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.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS