yayson: Prototype pollution in Store/LegacyStore deserialization — GHSA-325J-MG25-8Q58

Summary

# 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…

Timeline

Published by source

2026-09-11

Risk context

• Reported severity or threat level: critical.
• Reported CVSS score: 9.1 out of 10.
• Review exposure for the affected product or family: npm: yayson.

Product

npm: yayson

What to do

General, cautious steps (verify details in the official source):

• Prioritize patching or mitigation immediately (treat as actively risky).
• Identify affected product versions in your inventory and verify whether you are impacted.
• Apply vendor patches/updates or recommended mitigations as soon as available.
• Read the official advisory for exact affected versions and remediation steps.

Official advisory

• Read the official source
• CVE Record
• NVD

Evidence and provenance

Canonical advisory ID

GHSA-325J-MG25-8Q58

Source

GitHub

Vendor

GitHub

Published by source

2026-09-11

Last source activity

2026-09-11

Additional identifiers

CVE-2026-61534

Curated by

hlukh.ch

Related advisories and connections

These advisories are connected by shared CVE, product, vendor, source, or time signals.