CVE-2021-20234

Name: CVE-2021-20234
Creator: NVD / NIST
Published: 2021-04-01T14:15:13.123+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 6.5/10EPSS 1.07%

Last modified Jun 17, 2026

CVE-2021-20234 is a medium-severity vulnerability rated 6.5/10 on the CVSS scale. 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. EPSS estimates a 1.07% chance of exploitation in the next 30 days.

Description

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.

Metrics

CVSS 3.1

6.5/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

EPSS Probability

1.07%

60.7th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Zeromq	Libzmq	< 4.3.3

References

https://bugzilla.redhat.com/show_bug.cgi?id=1921972Issue Tracking, Patch, Third Party Advisory
https://github.com/zeromq/libzmq/security/advisories/GHSA-wfr2-29gj-5w87Exploit, Patch, Third Party Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=1921972Issue Tracking, Patch, Third Party Advisory
https://github.com/zeromq/libzmq/security/advisories/GHSA-wfr2-29gj-5w87Exploit, Patch, Third Party Advisory

Timeline

Published: Apr 1, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-20234?

How severe is CVE-2021-20234?

CVE-2021-20234 has a CVSS score of 6.5/10 (MEDIUM severity). The EPSS model estimates a 1.07% probability of exploitation in the next 30 days.

How do I fix CVE-2021-20234?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-20234?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST