p PatchFirst

CVE-2026-114613

CVE-2026-114613 · MessagePack: Unbounded memory leak in msgpack C extension on strict_map_key validation failure

This page contains facts from public vulnerability sources. Check the original advisory before updating.

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.

CVSS 7.5 · High · EPSS 0.3%

Published
Updated

Stack: system

Affected products and versions

  • msgpack-python

    Versions
    • < 1.2.3: Affected

    No fix published

  • python-msgpack Debian:12

    Versions
    • 1.0.3-2
    • 1.0.3-3
    • 1.1.2-1
    • 1.1.2-2
    • 1.1.2-3
    • 1.1.2-4
    • 1.2.1-1
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • python-msgpack Debian:13

    Versions
    • 1.0.3-3
    • 1.1.2-1
    • 1.1.2-2
    • 1.1.2-3
    • 1.1.2-4
    • 1.2.1-1
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • python-msgpack Debian:14

    Versions
    • 1.0.3-3
    • 1.1.2-1
    • 1.1.2-2
    • 1.1.2-3
    • 1.1.2-4
    • 1.2.1-1
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

Original sources

Check your server →