{"id":"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.","aliases":["GHSA-qq65-x72m-9wr8"],"modified":"2026-09-12T03:30:28.783637576Z","published":"2021-05-28T11:15:07.933Z","database_specific":{"unresolved_ranges":[{"vendor_product":"zeromq:zeromq","cpes":["cpe:2.3:a:zeromq:zeromq:*:*:*:*:*:*:*:*"],"extracted_events":[{"fixed":"4.3.3"}],"source":"CPE_RANGE"},{"source":"CPE_STRING","vendor_product":"fedoraproject:fedora","cpes":["cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:*"],"extracted_events":[{"introduced":"33"},{"last_affected":"33"}]},{"vendor_product":"redhat:ceph_storage","cpes":["cpe:2.3:a:redhat:ceph_storage:2.0:*:*:*:*:*:*:*"],"extracted_events":[{"introduced":"2.0"},{"last_affected":"2.0"}],"source":"CPE_STRING"},{"extracted_events":[{"introduced":"7.0"},{"last_affected":"7.0"}],"source":"CPE_STRING","vendor_product":"redhat:enterprise_linux","cpes":["cpe:2.3:o:redhat:enterprise_linux:7.0:*:*:*:*:*:*:*"]}]},"references":[{"type":"REPORT","url":"https://bugzilla.redhat.com/show_bug.cgi?id=1921976"},{"type":"FIX","url":"https://github.com/zeromq/libzmq/security/advisories/GHSA-qq65-x72m-9wr8"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/zeromq/libzmq","events":[{"introduced":"0"},{"fixed":"04f5bbedee58c538934374dc45182d8fc5926fa3"}],"database_specific":{"source":"DESCRIPTION","extracted_events":[{"introduced":"0"},{"fixed":"4.3.3"}]}}],"versions":["v4.3.2","v4.3.1","v4.3.0","v4.2.5","v4.2.4","v4.2.3","v4.2.2","v4.2.1","v4.2.0","v4.2.0-rc1","v3.1.0"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2021-20236.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"}]}