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

影響: pip:msgpack < 1.2.3 → 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. The report measured approximately 4 MiB retained pe…

GitHub Advisory Database에서 읽기

2026. 10. 28. 오전 12:04, GitHub Advisory Database에서 "MessagePack: Unbounded memory leak in msgpack C extension on strict_map_key validation failure"을(를) 게시했습니다 (유형: 취약점 권고). 심각도는 "높음"(high)입니다. 관련 기술: Python. CVE: CVE-2026-114613.