CVE-2026-107296: Mcollina MSGPACK5

Low severity, CVSS 3.7. EPSS: 0.3% chance of exploitation in the next 30 days.

msgpack5 is a msgpack v5 implementation for node.js and the browser. Prior to 6.1.0, decoding a negative signed 64-bit integer modifies the corresponding bytes in the caller-provided input buffer while computing the value. Applications that retain or reuse encoded input for integrity checks, logging, or later processing can observe silently corrupted data, while positive integers and other MessagePack value types are unaffected. This issue is fixed in version 6.1.0.

Affected products

• Mcollina MSGPACK5: before 6.1.0 (fixed in 6.1.0)

Published 2026-10-08. Last modified 2026-10-08.