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.

CVSS 3.1

3.7CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N

EPSS

0.3% chance of exploitation in the next 30 days; higher than 19% of CVEs (scores of 2026-10-25)

CWE

CWE-471

Published

2026-10-08

Modified

2026-10-14

Record from

the NVD, synced 2026-10-19

Packages (OSV)

References

• https://github.com/mcollina/msgpack5/commit/82b70393a824e1088a45a377548d1d9ab82faf91
• https://github.com/mcollina/msgpack5/releases/tag/v6.1.0
• https://github.com/mcollina/msgpack5/security/advisories/GHSA-qw35-55vc-rhgj

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