CVE-2026-114613 MessagePack Python - Denial of Service

MessagePack Python serializer prior to 1.2.3 contains a denial of service caused by memory leak in msgpack._cmsgpack when deserialization rejects keys with strict_map_key=True, letting attackers cause unbounded memory growth via crafted inputs, exploit requires attacker-controlled MessagePack data.

CVSS base score 7.5 /10
High
CISA KEV
Not listed
Public exploit
None known
Authentication
Not required
View the NVD record ↗

Details

Type
Denial of Service
Impact
Denial Of Service
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Published
22 October 2026
Updated
23 October 2026
Weakness
CWE-401

Vendor fix

Upgrade to version 1.2.3 or later.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

References

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