CVE-2021-20234: Zeromq Libzmq

Medium severity, CVSS 6.5. EPSS: 1.1% chance of exploitation in the next 30 days.

An uncontrolled resource consumption (memory leak) flaw was found in the ZeroMQ client in versions before 4.3.3 in src/pipe.cpp. This issue causes a client that connects to multiple malicious or compromised servers to crash. The highest threat from this vulnerability is to system availability.

Affected products

• Zeromq Libzmq: before 4.3.3 (fixed in 4.3.3)

Published 2021-04-01. Last modified 2026-06-17.