{"id":"UBUNTU-CVE-2021-20236","details":"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.","modified":"2026-04-22T12:45:34.260069Z","published":"2021-05-28T11:15:00Z","upstream":["CVE-2021-20236"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2021-20236"},{"type":"REPORT","url":"https://github.com/zeromq/libzmq/security/advisories/GHSA-qq65-x72m-9wr8"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2021-20236"}],"affected":[{"package":{"name":"zeromq3","ecosystem":"Ubuntu:Pro:14.04:LTS","purl":"pkg:deb/ubuntu/zeromq3@4.0.4+dfsg-2ubuntu0.1+esm3?arch=source&distro=esm-infra-legacy/trusty"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3.2.3+dfsg-2","3.2.4+dfsg-1","3.2.4+dfsg-2","3.2.4+dfsg-3","3.2.4+dfsg-4","4.0.3+dfsg-1","4.0.4+dfsg-2","4.0.4+dfsg-2ubuntu0.1","4.0.4+dfsg-2ubuntu0.1+esm1","4.0.4+dfsg-2ubuntu0.1+esm2","4.0.4+dfsg-2ubuntu0.1+esm3"],"ecosystem_specific":{"binaries":[{"binary_name":"libzmq3","binary_version":"4.0.4+dfsg-2ubuntu0.1+esm3"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2021/UBUNTU-CVE-2021-20236.json"}},{"package":{"name":"zeromq3","ecosystem":"Ubuntu:Pro:16.04:LTS","purl":"pkg:deb/ubuntu/zeromq3@4.1.4-7ubuntu0.1+esm2?arch=source&distro=esm-apps/xenial"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["4.0.5+dfsg-3ubuntu1~gcc5.1","4.0.5+dfsg-3ubuntu2","4.1.4-7","4.1.4-7ubuntu0.1","4.1.4-7ubuntu0.1+esm1","4.1.4-7ubuntu0.1+esm2"],"ecosystem_specific":{"binaries":[{"binary_name":"libzmq5","binary_version":"4.1.4-7ubuntu0.1+esm2"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2021/UBUNTU-CVE-2021-20236.json"}},{"package":{"name":"zeromq3","ecosystem":"Ubuntu:Pro:18.04:LTS","purl":"pkg:deb/ubuntu/zeromq3@4.2.5-1ubuntu0.2+esm2?arch=source&distro=esm-apps/bionic"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["4.2.1-4ubuntu1","4.2.2-1ubuntu2","4.2.3-1","4.2.3-1build1","4.2.5-1","4.2.5-1ubuntu0.1","4.2.5-1ubuntu0.2","4.2.5-1ubuntu0.2+esm1","4.2.5-1ubuntu0.2+esm2"],"ecosystem_specific":{"binaries":[{"binary_name":"libzmq5","binary_version":"4.2.5-1ubuntu0.2+esm2"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2021/UBUNTU-CVE-2021-20236.json"}},{"package":{"name":"zeromq3","ecosystem":"Ubuntu:Pro:20.04:LTS","purl":"pkg:deb/ubuntu/zeromq3@4.3.2-2ubuntu1.20.04.1~esm2?arch=source&distro=esm-apps/focal"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["4.3.2-1","4.3.2-2","4.3.2-2ubuntu1","4.3.2-2ubuntu1.20.04.1~esm1","4.3.2-2ubuntu1.20.04.1~esm2"],"ecosystem_specific":{"binaries":[{"binary_name":"libzmq5","binary_version":"4.3.2-2ubuntu1.20.04.1~esm2"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2021/UBUNTU-CVE-2021-20236.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"},{"type":"Ubuntu","score":"medium"}]}