Vulnerability library
Security checkAugust 06, 2026

Mermaid Architecture diagrams are vulnerable to prototype pollution

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Medium severitynpmmermaid

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Description

Rendering an untrusted architecture-beta diagram lets the diagram author write an arbitrary property with the value horizontal or vertical onto Object.prototype. A group id of __proto__ is accepted as a valid parent.

Recommendation

Update the mermaid package to the latest compatible version. Followings are version details:

  • Affected version(s): >= 11.5.0, < 11.16.1
  • Patched version(s): 11.16.1

References

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See something that needs correcting? Let us knowUpdated August 06, 2026