Vulnerability in Mcollina Msgpack5

CVE-2026-107296

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.

Published .

CVSS v3 metric

CVSS v3 base score 3.7 (Low). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N.

EPSS exploit prediction

No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-107296?
CVE-2026-107296 is a low-severity vulnerability in Mcollina Msgpack5, classified under Modification of Assumed-Immutable Data (MAID). CVSS score: 3.7/10. Published 2026-10-08.
How severe is CVE-2026-107296?
Low severity. CVSS v3 base score is 3.7 out of 10.