mermaid up to 11.9.0 cross site scripting

Summaryinfo

A vulnerability, which was classified as problematic, has been found in mermaid up to 11.9.0. This issue affects some unknown processing. Performing a manipulation results in cross site scripting. This vulnerability was named CVE-2025-54881. The attack may be initiated remotely. There is no available exploit. To fix this issue, it is recommended to deploy a patch.

Detailsinfo

A vulnerability classified as problematic has been found in mermaid up to 11.9.0. This affects an unknown functionality. The manipulation with an unknown input leads to a cross site scripting vulnerability. CWE is classifying the issue as CWE-79. The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. This is going to have an impact on integrity. The summary by CVE is:

Mermaid is a JavaScript based diagramming and charting tool that uses Markdown-inspired text definitions and a renderer to create and modify complex diagrams. In the default configuration of mermaid 10.9.0-rc.1 to 11.9.0, user supplied input for sequence diagram labels is passed to innerHTML during calculation of element size, causing XSS.

It is possible to read the advisory at github.com. This vulnerability is uniquely identified as CVE-2025-54881 since 07/31/2025. The exploitability is told to be easy. It is possible to initiate the attack remotely. No form of authentication is needed for exploitation. It demands that the victim is doing some kind of user interaction. The technical details are unknown and an exploit is not publicly available. The attack technique deployed by this issue is T1059.007 according to MITRE ATT&CK.

The vulnerability scanner Nessus provides a plugin with the ID 260126 (Linux Distros Unpatched Vulnerability : CVE-2025-54881), which helps to determine the existence of the flaw in a target environment.

Applying the patch 5c69e5fdb004a6d0a2abe97e23d26e223a059832 is able to eliminate this problem. The bugfix is ready for download at github.com.

The vulnerability is also documented in the vulnerability database at Tenable (260126). Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Productinfo

Name

• mermaid

Version

• 11.0
• 11.1
• 11.2
• 11.3
• 11.4
• 11.5
• 11.6
• 11.7
• 11.8
• 11.9.0

License

• open-source

CPE 2.3info

• 🔒
• 🔒
• 🔒

CPE 2.2info

• 🔒
• 🔒
• 🔒

CVSSv4info

CVSSv3info

CVSSv2info

Exploitinginfo

Threat Intelligenceinfo

Countermeasuresinfo

Timelineinfo

Sourcesinfo

Entryinfo

Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Discussion