Vulnerability library
Security checkSeptember 11, 2026

yayson: Prototype pollution in Store/LegacyStore deserialization

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High severitynpmyayson

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Description

Store/LegacyStore key internal lookup tables by the type, id, and relationship names from a JSON:API document. Because these were plain objects, a document with type: "__proto__" writes onto Object.prototype, polluting every object in the process.

Recommendation

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

  • Affected version(s): <= 4.2.0
  • Patched version(s): 4.3.0

References

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Related Issues

See something that needs correcting? Let us knowUpdated September 11, 2026