CVE-2026-57585

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.

CVSS 3.1

7.5CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS

0.5% chance of exploitation in the next 30 days; higher than 41% of CVEs (scores of 2026-10-25)

CWE

CWE-416

Published

2026-06-30

Modified

2026-10-25

Record from

the NVD, synced 2026-10-25

Affected

• msgpack:messagepack

Packages (OSV)

References

• https://github.com/msgpack/msgpack-python/commit/2c56ddb5d0025ed481d962c0f5d62d19dec7476d
• https://github.com/msgpack/msgpack-python/security/advisories/GHSA-6v7p-g79w-8964

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