CRITICAL 9.1 GitHub
CVE-2026-61534
yayson: Prototype pollution in Store/LegacyStore deserialization
# Summary
`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.
# Severity
Suggested CVSS v3.1 `AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H` (8.1). The guaranteed impact is process-wide DoS / logic corruption; escalation to authorization bypass or RCE is dependent on gadgets in the consuming applicat
Affected Products
- npm/yayson <= 4.2.0
References
- https://github.com/advisories/GHSA-325j-mg25-8q58
- https://github.com/confetti/yayson/security/advisories/GHSA-325j-mg25-8q58
- https://github.com/advisories/GHSA-325j-mg25-8q58
This critical severity vulnerability with a CVSS score of 9.1 was published on 2026-09-11 via GitHub. Affected: npm/yayson <= 4.2.0.
Risk Timeline
CVE Disclosed2026-09-11 · -1 days ago
Remediation Resources
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