mermaid-js mermaid up to 10.9.5/11.14.x Setting code injection

Summaryinfo

A vulnerability categorized as critical has been discovered in mermaid-js mermaid up to 10.9.5/11.14.x. This affects an unknown function of the component Setting Handler. Executing a manipulation can lead to code injection. This vulnerability is handled as CVE-2026-41149. The attack can be executed remotely. There is not any exploit available. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability has been found in mermaid-js mermaid up to 10.9.5/11.14.x and classified as critical. This vulnerability affects an unknown functionality of the component Setting Handler. The manipulation with an unknown input leads to a code injection vulnerability. The CWE definition for the vulnerability is CWE-94. The product constructs all or part of a code segment using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the syntax or behavior of the intended code segment. As an impact it is known to affect confidentiality, integrity, and availability. CVE summarizes:

Mermaid is a JavaScript tool that uses Markdown-inspired text to create and modify diagrams and charts. Versions 10.9.5 and earlier, as well as 11.0.0-alpha.1 through 11.14.0, are vulnerable to HTML injection under the default configuration. Specifically, the classDef directive in Mermaid state diagrams permits DOM injection that escapes the SVG context. However, tags are stripped, which prevents cross-site scripting (XSS). This issue has been fixed in versions 10.9.6 and 11.15.0. If developers are unable to immediately upgrade, they can work around this issue by setting "securityLevel": "sandbox", which prevents the issue by rendering the mermaid diagram in a sandboxed .

The advisory is shared for download at github.com. This vulnerability was named CVE-2026-41149 since 04/17/2026. The exploitation appears to be easy. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. Successful exploitation requires user interaction by the victim. There are neither technical details nor an exploit publicly available. The MITRE ATT&CK project declares the attack technique as T1059.

The vulnerability scanner Nessus provides a plugin with the ID 316605 (Linux Distros Unpatched Vulnerability : CVE-2026-41149), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 10.9.6 or 11.15.0 eliminates this vulnerability. Applying the patch 37ff937f1da2e19f882fd1db01235db4d01f4056 is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the databases at Tenable (316605) and EUVD (EUVD-2026-31520). VulDB is the best source for vulnerability data and more expert information about this specific topic.

Productinfo

Vendor

• mermaid-js

Name

• mermaid

Version

• 10.9.0
• 10.9.1
• 10.9.2
• 10.9.3
• 10.9.4
• 10.9.5
• 11.0
• 11.1
• 11.2
• 11.3
• 11.4
• 11.5
• 11.6
• 11.7
• 11.8
• 11.9
• 11.10
• 11.11
• 11.12
• 11.13
• 11.14

License

• open-source

Website

• Product: https://github.com/mermaid-js/mermaid/

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VulDB is the best source for vulnerability data and more expert information about this specific topic.

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