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Vulnerabilities / CVE-2021-20236

critical

CVE-2021-20236

zeromq: Stack overflow on server running PUB/XPUB socket

Published Modified CWE 120, 787
In the Trivy database since at least 24 Oct 2026, 07:11 UTCWhen it arrived before that build is not recorded.

Severity by source

NVD9.8CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Red Hat7.5CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H
Julia9.8CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Trivy's own label is CRITICAL. Rated critical by NVD, CBL-Mariner, Julia, Photon OS. Rated lower by Red Hat (medium), Ubuntu (medium).

Description

A flaw was found in the ZeroMQ server in versions before 4.3.3. This flaw allows a malicious client to cause a stack buffer overflow on the server by sending crafted topic subscription requests and then unsubscribing. The highest threat from this vulnerability is to confidentiality, integrity, as well as system availability.

Affected packages and fixed versions

SourcePackageFixed in
CBL-Mariner 1.0zeromq0:4.3.4-1.cm1
julia::Julia Ecosystem Security AdvisoriesZeroMQ_jll4.3.4+0
Photon OS 1.0zeromq4.3.4-1.ph1
Photon OS 2.0zeromq4.3.4-1.ph2
Photon OS 3.0zeromq4.3.4-1.ph3
conan::GitLab Advisory Database Communityzeromq4.3.3
debian 10zeromq3no fix listed
debian 11zeromq34.3.3-1
debian 12zeromq34.3.3-1
debian 13zeromq34.3.3-1
debian 14zeromq34.3.3-1
debian 9zeromq3no fix listed
Show all 16 entries from 16 sources
SourcePackageFixed in
CBL-Mariner 1.0zeromq0:4.3.4-1.cm1
julia::Julia Ecosystem Security AdvisoriesZeroMQ_jll4.3.4+0
Photon OS 1.0zeromq4.3.4-1.ph1
Photon OS 2.0zeromq4.3.4-1.ph2
Photon OS 3.0zeromq4.3.4-1.ph3
conan::GitLab Advisory Database Communityzeromq4.3.3
debian 10zeromq3no fix listed
debian 11zeromq34.3.3-1
debian 12zeromq34.3.3-1
debian 13zeromq34.3.3-1
debian 14zeromq34.3.3-1
debian 9zeromq3no fix listed
echozeromq34.3.3-1
Red Hatzeromq3no fix listed
ubuntu 18.04-ESMzeromq3no fix listed
ubuntu 20.04-ESMzeromq3no fix listed

References

Vulnerability data compiled from the Trivy vulnerability database (trivy-db, Aqua Security, Apache License 2.0), which aggregates third-party advisories. CVE records are published by The MITRE Corporation under the CVE Terms of Use; CVE is a trademark of MITRE. This product uses data from the NVD API but is not endorsed or certified by the NVD. Severity, titles and advisory data from the GitHub Advisory Database (CC BY 4.0), Red Hat security data (CC BY 4.0) and the other sources linked on each entry. Entries may be summarised or re-formatted; the linked original is the authoritative record.