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.
Metrics
Affected Vendors & Products
References
History
Fri, 23 Oct 2026 22:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Metrics |
ssvc
|
Fri, 23 Oct 2026 12:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Weaknesses | CWE-772 | |
| References |
| |
| Metrics |
threat_severity
|
threat_severity
|
Fri, 23 Oct 2026 04:45:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| First Time appeared |
Msgpack
Msgpack msgpack-python |
|
| Vendors & Products |
Msgpack
Msgpack msgpack-python |
Fri, 23 Oct 2026 00:45:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | 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. | |
| Title | MessagePack: Unbounded memory leak in msgpack C extension on strict_map_key validation failure | |
| Weaknesses | CWE-401 | |
| References |
| |
| Metrics |
cvssV3_1
|
Status: PUBLISHED
Assigner: GitHub_M
Published: 2026-10-22T18:22:40.544Z
Updated: 2026-10-23T21:08:06.271Z
Reserved: 2026-10-21T20:34:25.599Z
Link: CVE-2026-114613
Updated: 2026-10-23T17:32:59.556Z
Status : Awaiting Analysis
Published: 2026-10-22T19:17:37.733
Modified: 2026-10-23T21:17:21.823
Link: CVE-2026-114613