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Fencer Intel
high 7.5

CVE-2026-114613 json

MessagePack: Unbounded memory leak in msgpack C extension on strict_map_key validation failure

published 18d ago modified 13d ago also EUVD-2026-108280 , GHSA-j586-36cw-2gc2

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 45%
public exploits
0
none known

Summary

MessagePack is the serializer implementation for Python msgpack.org. Prior to 1.2.3, the msgpack-python C extension (msgpack._cmsgpack) leaks a decoded map value when deserialization rejects a key with strict_map_key=True (the default). Repeated malformed inputs can cause unbounded process memory growth and denial of service in applications that deserialize attacker-controlled MessagePack data. Both unpackb() and the streaming Unpacker API are affected. The pure-Python fallback does not exhibit this leak in the reported tests. This issue is fixed in version 1.2.3.

Patch / fix

  • pypi msgpack 1.2.3
  • msgpack messagepack 1.2.3
  • python-msgpack Azure Linux 3.0 1.2.3-1

azure linux advisories AZL-111044

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

Is CVE-2026-114613 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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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-2026-114613 updated cvss 7.5

msgpack: msgpack: Denial of Service via memory leak during map deserialization

  • Red Hat Lightspeed Services for Advanced Cluster Management lightspeed-services-acm/ocp-rules-rhel9 Red Hat Pen Drive Powered by Red Hat Lightspeed pen-drive/pen-drive-scanner-rhel9
    affected: workaround, no fix available
  • Red Hat AI Inference Server rhaii/vllm-cpu-rhel9, rhaii/vllm-tpu-rhel9, rhaii/vllm-cuda-rhel9, rhaii/vllm-rocm-rhel9, rhaiis/vllm-tpu-rhel9, rhaii/vllm-gaudi-rhel9, +3 more Red Hat Ansible Automation Platform 2 automation-controller 4.6.34-1.el8ap, 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, +4 more
    affected: workaround, no fix available, no fix planned “Will not fix”
  • Red Hat Enterprise Linux 10 python-msgpack 1.1.1-1.el10_2 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 Lightspeed Services for OCP lightspeed-services-ocp/ocp-rules-rhel9 Red Hat OpenShift AI (RHOAI) rhai/guidellm-rhel9, rhoai/odh-vllm-cuda-rhel9, rhoai/odh-vllm-rocm-rhel9, rhoai/odh-feature-server-rhel9, rhoai/odh-th-torch-cuda-py312-rhel9, rhoai/odh-th-torch-rocm-py312-rhel9, +26 more Red Hat OpenShift Container Platform 4 python3-msgpack, python-msgpack 1.1.1-1.el10_2 Red Hat OpenStack Platform 16.2 python3-msgpack
    +4 more products
    Red Hat OpenStack Platform 17.1 python3-msgpack Red Hat OpenStack Platform 18.0 python-msgpack 1.1.1-1.el10_2 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
    affected: workaround, no fix available
  • Red Hat Ansible Automation Platform 2 ansible-automation-platform-26/lightspeed-rhel9, ansible-automation-platform-27/lightspeed-rhel9, ansible-automation-platform/automation-dashboard-rhel9
    not affected: vulnerable code not in execute path
  • Red Hat Enterprise Linux 8 python3.12-pip-wheel, python3.12-pip 23.2.1-4.el8 Red Hat Enterprise Linux 9 python3-pip, python3.14-pip, python3-pip-wheel, python3.12-pip-wheel, python3.14-pip-wheel, python-pip 23.3.2-11.el10_2, +2 more Red Hat Enterprise Linux 10 python-pip 23.3.2-11.el10_2, python3.14-pip 25.2-3.el10_2.5
    not affected: vulnerable code not present
  • Red Hat OpenShift AI (RHOAI) rhoai/odh-vllm-gaudi-rhel9, rhoai/odh-kserve-agent-rhel9, rhoai/odh-kserve-router-rhel9, rhoai/odh-kserve-controller-rhel9, rhoai/odh-th06-cuda130-torch291-py312-rhel9
    not affected: component 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
17d ago

Exploit prediction

0.54% chance of exploitation in the next 30 days, higher than 45% of all scored CVEs (FIRST EPSS, 2026-11-09).

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

Affected packages

ecosystem package affected fixed in
pypi msgpack
<1.2.3
1.2.3

Affected products

  • msgpack msgpack-python

Classification

Weakness
  • CWE-401 Missing Release of Memory after Effective Lifetime
  • CWE-416 Use After Free

References

Sources

Fencer Intel 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.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.