What’s Vulnerable › Vulnerabilities

CVE-2025-54881: Mermaid improperly sanitizes of sequence diagram labels leading to XSS

• Severity: medium (CVSS 5.3 v4.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.8% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2025-08-19 · updated 2026-06-17
• Weakness: CWE-79

Description

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.

Affected products

• mermaid-js mermaid: from 10.9.0-rc.1, <= 11.9.0

References

• https://github.com/mermaid-js/mermaid/commit/5c69e5fdb004a6d0a2abe97e23d26e223a059832
• https://github.com/mermaid-js/mermaid/commit/685516a85ec1df64cefd4fd15f26533be87d458e
• https://github.com/mermaid-js/mermaid/security/advisories/GHSA-7rqq-prvp-x9jh

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