Skip to main content

msgpack-python CVE-2026-57585

| EUVDEUVD-2026-40423 HIGH
Use After Free (CWE-416)
2026-06-30 security-advisories@github.com
Buffer Overflow Python Use After Free Memory Corruption Red Hat Messagepack Msgpack
7.5
CVSS 3.1 · Vendor: github
Share

Severity by source

Vendor (github) PRIMARY
7.5 HIGH
AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
vuln.today AI
5.9 MEDIUM

Network-reachable and unauthenticated, but exploitation depends on the app reusing an Unpacker after a caught error, so AC:H; impact is crash-only, hence C:N/I:N/A:H.

3.1 AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
4.0 AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
SUSE
HIGH
qualitative
Red Hat
7.5 HIGH
qualitative

Primary rating from Vendor (github).

CVSS VectorVendor: github

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

Lifecycle Timeline

2
Patch available
Jun 30, 2026 - 23:01 EUVD
Analysis Generated
Jun 30, 2026 - 22:30 vuln.today

Blast Radius

ecosystem impact
† from your stack dependencies † transitive graph · vuln.today resolves 4-path depth
  • 29 pypi packages depend on msgpack (16 direct, 13 indirect)

Ecosystem-wide dependent count for version 1.2.1.

DescriptionCVE.org

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.

Articles & Coverage 1

News 5 New Python Vulnerabilities - 2 Critical, 3 High Severity Jul 01, 2026

AnalysisAI

Denial of service in the msgpack-python serialization library (versions prior to 1.2.1) lets remote attackers crash a process via an out-of-bounds read when an application reuses an Unpacker instance after a previously raised error was caught. Sending malformed MessagePack data that triggers an error, then feeding further data to the same Unpacker, can drive the process to a SEGV. No public exploit has been identified at time of analysis, and EPSS data was not provided, but the CVSS 3.1 score of 7.5 (availability-only) reflects a straightforward, unauthenticated crash condition.

Technical ContextAI

msgpack-python is the CPython binding (largely Cython/C) for the MessagePack binary serialization format, widely used to deserialize compact binary payloads in RPC frameworks, caches, message queues, and ML tooling. The defect lives in the Unpacker streaming-decode object: after an exception is raised and caught mid-stream, internal buffer/offset state is left inconsistent, so a subsequent feed/unpack on the same instance reads past valid buffer bounds. NVD classifies this as CWE-416 (Use After Free) and the GitHub tags add Buffer Overflow / Memory Corruption, though the advisory text describes the concrete manifestation as an out-of-bounds read causing a crash rather than confirmed exploitable memory corruption.

RemediationAI

Upgrade msgpack to the fixed release - Vendor-released patch: 1.2.1 - by pinning msgpack>=1.2.1 in requirements and rebuilding/redeploying, per advisory GHSA-6v7p-g79w-8964 (https://github.com/msgpack/msgpack-python/security/advisories/GHSA-6v7p-g79w-8964). If immediate upgrade is not possible, the targeted workaround is to stop reusing an Unpacker instance after an exception: discard the Unpacker and instantiate a fresh one (or drop/reset the connection) whenever a decode error is caught, which removes the inconsistent-state trigger at the cost of losing any buffered stream continuation. Additionally, validate or size-limit untrusted MessagePack input and isolate decoding in a restartable worker so a SEGV degrades to a recoverable restart rather than a full outage; review the fixing commit 2c56ddb5d0025ed481d962c0f5d62d19dec7476d to confirm coverage of your usage pattern.

More in Python

View all
CVE-2025-24016 CRITICAL POC
9.9 Feb 10

Wazuh SIEM platform versions 4.4.0 through 4.9.0 contain an unsafe deserialization vulnerability in the DistributedAPI t
CVE-2025-27520 CRITICAL POC
9.8 Apr 04

BentoML version 1.4.2 and earlier contains an unauthenticated remote code execution vulnerability through insecure deser
CVE-2025-2945 CRITICAL POC
9.9 Apr 03

pgAdmin 4 contains critical remote code execution vulnerabilities in the Query Tool download and Cloud Deployment endpoi
CVE-2013-5093 MEDIUM POC
6.8 Sep 27

The renderLocalView function in render/views.py in graphite-web in Graphite 0.9.5 through 0.9.10 uses the pickle Python

CVE-2025-32375 CRITICAL POC
9.8 Apr 09

BentoML is a Python library for building online serving systems optimized for AI apps and model inference. Rated critica
CVE-2014-0224 HIGH POC
7.4 Jun 05

OpenSSL before 0.9.8za, 1.0.0 before 1.0.0m, and 1.0.1 before 1.0.1h does not properly restrict processing of ChangeCiph
CVE-2024-21644 HIGH POC
7.5 Jan 08

pyLoad download manager version prior to 0.5.0b3.dev77 exposes the Flask SECRET_KEY through an unauthenticated endpoint.
CVE-2026-33017 CRITICAL POC
9.3 Mar 17

Langflow (a visual LLM pipeline builder) contains a critical unauthenticated code execution vulnerability (CVE-2026-3301
CVE-2017-9462 HIGH POC
8.8 Jun 06

In Mercurial before 4.1.3, "hg serve --stdio" allows remote authenticated users to launch the Python debugger, and conse
CVE-2026-49869 CRITICAL POC
10.0 Jun 26

Unauthenticated remote code execution affects Kestra OSS (the open-source event-driven orchestration platform) prior to

CVE-2026-39987 CRITICAL POC
9.3 Apr 08

Unauthenticated remote code execution in Marimo ≤0.20.4 allows attackers to execute arbitrary system commands via the `/
CVE-2024-21645 MEDIUM POC
5.3 Jan 08

pyLoad is the free and open-source Download Manager written in pure Python. Rated medium severity (CVSS 5.3), this vulne

Same weakness CWE-416 – Use After Free

View all
CVE-2019-0708 CRITICAL POC
9.8
CVE-2015-5119 CRITICAL POC
9.8
CVE-2014-0322 HIGH POC
8.8
CVE-2012-4792 HIGH POC
8.8
CVE-2009-4324 HIGH POC
7.8
CVE-2015-0313 CRITICAL POC
9.8
CVE-2015-5122 CRITICAL POC
9.8
CVE-2013-2551 HIGH POC
8.8

Same technique Buffer Overflow

View all
CVE-2017-7269 CRITICAL POC
9.8
CVE-2015-5119 CRITICAL POC
9.8
CVE-2015-3113 CRITICAL POC
9.8
CVE-2011-2462 CRITICAL POC
9.8
CVE-2020-0796 CRITICAL POC
10.0
CVE-2019-11043 CRITICAL POC
9.8
CVE-2009-0927 HIGH POC
8.8
CVE-2012-1889 HIGH POC
8.8

Vendor StatusVendor

SUSE

Severity: Important
Product Status
SUSE Linux Enterprise High Performance Computing 15 SP4-ESPOS Fixed
SUSE Linux Enterprise High Performance Computing 15 SP4-LTSS Fixed
SUSE Linux Enterprise High Performance Computing 15 SP5-ESPOS Fixed
SUSE Linux Enterprise High Performance Computing 15 SP5-LTSS Fixed
SUSE Linux Enterprise High Performance Computing 15 SP7 SUSE Linux Enterprise Module for Public Cloud 15 SP7 SUSE Linux Enterprise Server 15 SP7 SUSE Linux Enterprise Server for SAP Applications 15 SP7 Fixed

Share

CVE-2026-57585 vulnerability details – vuln.today
Back

This site uses cookies essential for authentication and security. No tracking or analytics cookies are used. Privacy Policy