CVE-2026-57585: Msgpack Messagepack

High severity, CVSS 7.5. EPSS: 0.5% chance of exploitation in the next 30 days.

MessagePack is the serializer implementation for Python msgpack.org. Prior to 1.2.1, there is an Out-of-bounds read/crash on Unpacker reuse after a caught error, potentially leading to a DoS attack. If the Unpacker is used repeatedly after an error occurs, the process may crash with a SEGV. This issue has been fixed in version 1.2.1.

Affected products

• Msgpack Messagepack: before 1.2.1 (fixed in 1.2.1)

Published 2026-06-30. Last modified 2026-08-06.