HIGH 7.5 NVD
CVE-2026-114613
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 valu
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.
References
- https://github.com/msgpack/msgpack-python/commit/620b0eb4c89cd72d4098564537624d9dbb2ce141
- https://github.com/msgpack/msgpack-python/releases/tag/v1.2.3
- https://github.com/msgpack/msgpack-python/security/advisories/GHSA-j586-36cw-2gc2
This high severity vulnerability with a CVSS score of 7.5 was published on 2026-10-22 via NVD.
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