CVE intelligence

CVE-2026-114613

Vulnerability intelligence

Published Oct 22, 2026Sources checked Oct 27, 2026

7.5HIGHCVSS out of 10

What this means

Review the available evidence

CVE-2026-114613 and is rated High severity with a CVSS score of 7.5. It is not in the current CISA KEV record we collected. That does not prove exploitation has not occurred.

What to do next

Remediation and response

Microsoft Security Response Center guidance

Vendor revision: Oct 26, 2026

Release Notes

CISA KEVNot listedBased on the latest collected catalog

EPSS0.4%Estimated 30-day exploitation probability

Ransomware useNot markedCISA KEV ransomware field

Threat actors0Source-linked actor relationships

Overview

What is CVE-2026-114613?

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.

Source: NVD