Skip to content
Fencer Vulns
high 7.5

CVE-2026-57585 json

MessagePack: Out-of-bounds read/crash on Unpacker reuse after caught error

published 2026-06-19 4 mo ago modified 2026-10-25 14 d ago also GHSA-6v7p-g79w-8964 , PYSEC-2026-3625 , EUVD-2026-40423

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 42%
public exploits
0
none known

Summary

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.

Patch / fix

  • pypi msgpack 1.2.1
  • msgpack messagepack 1.2.1
  • python-msgpack Debian 14 1.1.2-3

debian advisories DEBIAN-CVE-2026-57585

  • python-msgpack SLES for SAP 15 SP6, SLES 15 SP6-LTSS, SLE Module for Python 3 15 SP7 1.0.7-150600.3.5.1
  • python-msgpack SLES for SAP 15 SP5, SLES for SAP 15 SP4, SLES 15 SP5-LTSS +5 more 1.0.7-150400.10.9.1
  • python-msgpack Linux Micro 6.1 1.0.5-slfo.1.1_2.1
  • python-msgpack-python Manager Client Tools 12 0.4.6-8.8.1
  • python-msgpack SLES for SAP 15 SP6, SLES for SAP 15 SP5, SLES for SAP 15 SP4 +11 more 0.5.6-150100.3.6.1
  • python-msgpack Linux Micro 6.0 1.0.5-2.1

suse advisories SUSE-SU-2026:4443-1SUSE-SU-2026:3932-1SUSE-SU-2026:23169-1SUSE-SU-2026:3297-1SUSE-SU-2026:3113-1SUSE-SU-2026:22704-1

  • python-msgpack openSUSE Tumbleweed 1.2.1-1.1
  • python-msgpack openSUSE Leap 16.0 1.1.0-160000.3.1

opensuse advisories openSUSE-SU-2026:11586-1openSUSE-SU-2026:21239-1

  • python-msgpack Azure Linux 3.0 1.0.5-3

azure linux advisories AZL-91746

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-57585 updated cvss 7.5

msgpack: MessagePack for Python: Denial of Service via Unpacker reuse after error

  • Red Hat Enterprise Linux 9 python-pip, python3-pip, python3.12-pip, python3.14-pip, python3-pip-wheel, python3.12-pip-wheel, +1 more Red Hat Enterprise Linux 10 python-msgpack
    affected: workaround, no fix available
  • Red Hat AI Inference Server 3.2 rhaiis/vllm-cuda-rhel9 1790621718, rhaiis/vllm-rocm-rhel9 1790621713
    fixed: vendor fix RHSA-2026:73929
  • Red Hat AI Inference Server 3.4 rhaii/vllm-cpu-rhel9 1790075793, rhaii/vllm-cuda-rhel9 1790090131, rhaii/vllm-rocm-rhel9 1790109620
    fixed: vendor fix RHSA-2026:70965
  • Red Hat Pen Drive Powered by Red Hat Lightspeed pen-drive/pen-drive-scanner-rhel9 Red Hat AI Inference Server rhaii/vllm-tpu-rhel9, rhaiis/vllm-tpu-rhel9, rhaii/vllm-gaudi-rhel9, rhaiis/vllm-spyre-rhel9 Red Hat Ansible Automation Platform 2 automation-controller, ansible-automation-platform-26/hub-rhel9, ansible-automation-platform-27/hub-rhel9, ansible-automation-platform-24/controller-rhel8, ansible-automation-platform-25/controller-rhel8, ansible-automation-platform-26/controller-rhel9, +5 more
    not affected: vulnerable code not present
  • Red Hat Enterprise Linux 8 python3.12-pip, python3.12-pip-wheel
    not affected: vulnerable code not in execute path
  • Red Hat Enterprise Linux 10 python-pip, python3.14-pip
    not affected: component not present
  • Red Hat Enterprise Linux AI (RHEL AI) 3 rhelai3/bootc-cuda-rhel9, rhelai3/bootc-rocm-rhel9, rhelai3/bootc-gaudi-rhel9, rhelai3/bootc-aws-cuda-rhel9, rhelai3/bootc-gcp-cuda-rhel9, rhelai3/bootc-azure-cuda-rhel9, +1 more Red Hat OpenShift AI (RHOAI) rhai/guidellm-rhel9, rhoai/odh-vllm-gaudi-rhel9, rhoai/odh-kserve-agent-rhel9, rhoai/odh-kserve-router-rhel9, rhoai/odh-feature-server-rhel9, rhoai/odh-kserve-controller-rhel9, +29 more Red Hat OpenShift Container Platform 4 python-msgpack, python3-msgpack, openshift4/ose-ironic-rhel9, openshift4/ose-ironic-agent-rhel9 Red Hat OpenShift Container Platform 5 openshift5/ose-ironic-rhel9, openshift5/ose-ironic-agent-rhel9 Red Hat OpenStack Platform 16.2 python3-msgpack, rhosp-rhel8/openstack-iscsid, rhosp-rhel8/openstack-ec2-api, rhosp-rhel8/openstack-horizon, rhosp-rhel8/openstack-tempest, rhosp-rhel8/openstack-aodh-api, +88 more Red Hat OpenStack Platform 17.1 python3-msgpack
    +3 more products
    Red Hat OpenStack Platform 18.0 python-msgpack, rhoso/openstack-cinder-api-rhel9, rhoso/openstack-glance-api-rhel9, rhoso/openstack-cinder-base-rhel9, rhoso/openstack-manila-share-rhel9, rhoso/openstack-nova-compute-rhel9, +4 more Red Hat Quay 3 quay/quay-rhel8, quay/quay-rhel9 Red Hat Satellite 6 satellite/iop-puptoo-rhel9, satellite/iop-yuptoo-rhel9, satellite/iop-advisor-engine-rhel9, satellite/iop-insights-engine-rhel9
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
partial
Assessed
4 mo ago

Exploit prediction

0.49% chance of exploitation in the next 30 days, higher than 42% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
GitHub 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
OSV 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected packages

ecosystem package affected fixed in
pypi msgpack
<1.2.1
1.2.1

Affected products

  • msgpack msgpack-python

Classification

Weakness

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.