CVE-2026-41591: Improper Neutralization of Input During Web Page Generation

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 , , etc. and inject arbitrary HTML/JavaScript, resulting in cross-site scripting. This issue has been patched in mar...

GHSA-X9FJ-57FH-C8WQ Marko: XSS via case-insensitive script/style closing tag bypass in runtime HTML escaping

Summary When dynamic text is interpolated into a or 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 or block could break out of the tag with , , etc. and inject arbitrary HTML/JavaScript, resulting in...

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

Summary When dynamic text is interpolated into a or 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 or block could break out of the tag with , , etc. and inject arbitrary HTML/JavaScript, resulting in...

Cross-site Scripting (XSS)

Overview @marko/runtime-tags is an Optimized runtime for Marko templates. Affected versions of this package are vulnerable to Cross-site Scripting XSS in the handling of interpolated values within or tags due to improper case-insensitive detection of closing tags. An attacker can execute arbitrar...