CVE-2026-57585 | MessagePack is the serializer implementation for Python msgp… | CVSS 7.5 HIGH

Description

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.

Metadata

CVE ID: CVE-2026-57585
State: PUBLISHED
Assigner: GitHub_M
Reserved: 2026-06-24 18:49 UTC
Published: 2026-06-30 21:36 UTC
Last updated: 2026-06-30 21:36 UTC
Primary CWE: CWE-416
CWE-416: Use After Free
Vendor / Product: msgpack / msgpack-python
Sources: cve.org · NVD

Severity & Metrics

7.5 HIGH CVSS 3.1

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

Affected products (1)

Vendor	Product	Platform	Versions
msgpack	msgpack-python	—	< 1.2.1

Weakness (CWE)

CWE	Source	Description
CWE-416	cna	CWE-416: Use After Free

CVSS scores (1)

Score	Severity	Version	Source	Vector
7.5	HIGH	3.1	cna	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

References (2)

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