Vuln Signal Radar
public-safe defensive signal
Agent JSON
CRITICALpublic-safe

CVE-2026-61534

NVD: Yayson is a library for serializing and reading JSON API data in JavaScript. NVD: Prior to 4.3.0, Store and LegacyStore use attacker-controlled JSON:API type, id, and relationship names as keys in plain-object lookup tables in src/yayson/store.ts and src/yayson/legacy-store.ts. NVD: A document whose type is __proto__ causes model-cache writes to modify Object.prototype, with the attacker controlling the polluted property name through id and its value through attributes.

CVSS
9.1 Severity
CRITICAL EPSS
0.0078 (54) KEV
-

Source-published summary

NVD: Yayson is a library for serializing and reading JSON API data in JavaScript. NVD: Prior to 4.3.0, Store and LegacyStore use attacker-controlled JSON:API type, id, and relationship names as keys in plain-object lookup tables in src/yayson/store.ts and src/yayson/legacy-store.ts. NVD: A document whose type is __proto__ causes model-cache writes to modify Object.prototype, with the attacker controlling the polluted property name through id and its value through attributes.

Possible impact

Source describes service availability risk. Possible impact: The affected service may become unavailable or unreliable.

Affected context

Affected product or version requires source confirmation.

Remediation / advisory

Patch confirmed by source text; fixed version context: version.

Why it matters

Source describes service availability risk. Possible impact: The affected service may become unavailable or unreliable.; CVSS 9.1 (CRITICAL); EPSS percentile 54; not listed in KEV; Patch confirmed by source text; fixed version context: version; sources: NVD, OSV.

What to verify

Confirm affected product/version, vendor advisory, patch or mitigation, and exposure.

Exposure hint

exposure unknown

Impact tags

service availability review

Urgency reasons

CVSS CRITICALvendor advisory presentrecent updateremediation reference present

Source-derived note

Summary derived from NVD / OSV description; unsafe procedural detail is not shown.

Redaction metadata

source summary used
True
fallback summary used
False
unsafe procedural detail present
false
raw source displayed
false
public summary redacted
true

Remediation handoff

Public-safe static handoff for human/Codex remediation planning. Scan, patch, external execution, and auto remediation are disabled.

Handoff JSON Handoff Markdown Safe Codex prompt

Safety note

This radar shows source-published defensive context only. Exploit procedures, exploit strings, scanner commands, and auto-remediation are not provided.

Official references