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 Databaseで読む

2026/10/28 00:04、GitHub Advisory Databaseが「MessagePack: Unbounded memory leak in msgpack C extension on strict_map_key validation failure」を公開しました (種別: 脆弱性アドバイザリ)。重大度は「重要」(high) です。関連する技術: Python。CVE: CVE-2026-114613。