CVE-2026-61534: yayson: Prototype pollution in Store/LegacyStore deserialization

September 11, 2026

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.

References

github.com/advisories/GHSA-325j-mg25-8q58
github.com/confetti/yayson/security/advisories/GHSA-325j-mg25-8q58
nvd.nist.gov/vuln/detail/CVE-2026-61534

Code Behaviors & Features

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