HOMEVULNERABILITIESCVE-2021-20234
MEDIUM

CVE-2021-20234

CWE-400Published: April 1, 2021· Updated: Jun 17, 2026

6.5
CVSS v3.1

Official 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.

NVD Source

Technical Analysis

CVE-2021-20234 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

Exploitation does not require any privileges, though user interaction (Required) is needed, which slightly reduces the risk of mass automated attacks.

A successful exploit results in availability disruption (denial of service), with a CVSS base score of 6.5.

CVSS v3.1 Vector Breakdown

Exploitability
Attack VectorNetwork
Attack ComplexityLow
Privileges Req.None
User InteractionRequired
ScopeUnchanged
Impact
ConfidentialityNone
IntegrityNone
AvailabilityHigh
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

Affected Vendors & Products

zeromq1 product(s)
libzmq
Source: NVD CPE · 1 total CPE entries

Exploit & PoC Resources

NO KNOWN EXPLOITNo public exploit confirmed at this time
Exploit-DB
Offensive Security exploit database
GitHub PoC Search
Community PoC repositories
Rapid7 / Metasploit
Metasploit module search
PacketStorm
Security advisories & exploits
NVD Detail
Official NIST entry
MITRE CVE
CVE Program entry
External links open in a new tab. Always verify in a controlled environment before use.

Official Patches & Advisories

PATCHhttps://bugzilla.redhat.com/show_bug.cgi?id=1921972
PATCHhttps://github.com/zeromq/libzmq/security/advisories/GHSA-wfr2-29gj-5w87
PATCHhttps://bugzilla.redhat.com/show_bug.cgi?id=1921972
PATCHhttps://github.com/zeromq/libzmq/security/advisories/GHSA-wfr2-29gj-5w87

All References (4)

→
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

Quick Facts

CVE IDCVE-2021-20234
CVSS Score6.5 / 10
SeverityMEDIUM
WeaknessCWE-400
CISA KEVNo
Affected1 vendor(s)
PublishedApr 1, 2021

Related CVEs (CWE-400)

CVE-2023-30769
9.8
CVE-2019-2259
9.8
CVE-2018-11936
9.8
CVE-2019-10952
9.8
CVE-2015-4412
9.8
CVE-2026-30141
9.8

Recommended Actions

  • →Apply vendor patches immediately
  • →Monitor CVE-2021-20234 in threat intel feeds
  • →Review IDS/IPS signatures for exploitation attempts
Data sourced from NVD (NIST), CISA KEV, and EPSS (FIRST). Analysis generated by CTIWatch. CVE data is provided under the NVD usage policy.
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