MessagePack: Unbounded memory leak in msgpack C extension on strict_map_key validation failure
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 s…
Severity high: primary CNA CVSS 7.5 v3.1 (worst CNA-provided scenario) Not listed in this KEV snapshot. Forecast present in this snapshot.
Published 2026-10-22T18:22:40.544Z. Updated 2026-10-23T21:08:06.271Z.