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…

在 GitHub Advisory Database 阅读

2026/10/28 00:04，GitHub Advisory Database 发布了“MessagePack: Unbounded memory leak in msgpack C extension on strict_map_key validation failure”（类型：漏洞公告）。严重程度为“高危”（high）。相关技术：Python。CVE：CVE-2026-114613。