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CVE-2026-114613

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

Description (CNA)

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.

Affected (CNA)

Vendor / productVersions
msgpack / msgpack-pythonaffected < 1.2.3

CWE

CWE-401

References

ADP enrichment

CISA-ADP

No English description supplied.

No references supplied.