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CVE-2026-41591

27
FAUCET Score

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.

First published: May 8, 2026Last modified: May 8, 2026

Impacted Technologies

VendorProductVersion(s)CPE
Marko-JsMarko
@marko/runtime-tags < 6.0.164, marko < 5.38.36CNA affected

CVSS Data

CVSS version used by this source: 3.1

6.4MEDIUM

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 Impact
LOW
Integrity Impact
LOW
Availability Impact
NONE
Exploitability Score
3.1
Impact Score
2.7
CvssVersion
3.1

Exploit Intelligence

EPSS Score
0.20%
Probability of exploitation in next 30 days
EPSS Percentile
9.5%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0020 is in the 7th percentile among its peer group of 21,974 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.0 Mastodon, and 0.1 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.0 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (2)

npmpatch availablevia ghsa
Product: markoFixed in: 5.38.36
npmpatch availablevia ghsa
Product: @marko/runtime-tagsFixed in: 6.0.164

Vendor Advisories (1)

npmGHSA-x9fj-57fh-c8wqmedium

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

Apr 22, 2026

References

github.com / marko-js/marko/security/advisories/GHSA-x9fj-57fh-c8wq