CVE-2026-114613
MessagePack is the serializer implementation for Python msgpack.org
- Risk score
- 65/100
- CVSS
- 7.5 v3.1
- Exploit chance (30 days)
- 0.3%
- Published
- 22 Oct 2026
Open in the live forecast Today's forecast
What to know
- What it is
- 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 …
- Affected
- See advisory
- Fix
- Upgrade the product to 1.2.3 or later.
- Exploitation
- No known exploitation
Why it is Amber
- CVSS 7.5 high
- Remotely exploitable without logging in
- On your watchlist: python
References
Original 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.
Last activity 22 Oct 2026. Patch Forecast updates every hour.