{"id":"CVE-2021-20235","details":"There's a flaw in the zeromq server in versions before 4.3.3 in src/decoder_allocators.hpp. The decoder static allocator could have its sized changed, but the buffer would remain the same as it is a static buffer. A remote, unauthenticated attacker who sends a crafted request to the zeromq server could trigger a buffer overflow WRITE of arbitrary data if CURVE/ZAP authentication is not enabled. The greatest impact of this flaw is to application availability, data integrity, and confidentiality.","modified":"2026-03-20T04:04:57.958349Z","published":"2021-04-01T14:15:13.217Z","related":["GHSA-fc3w-qxf5-7hp6"],"references":[{"type":"FIX","url":"https://bugzilla.redhat.com/show_bug.cgi?id=1921983"},{"type":"FIX","url":"https://github.com/zeromq/libzmq/security/advisories/GHSA-fc3w-qxf5-7hp6"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/zeromq/libzmq","events":[{"introduced":"097bf26e8dacf73abc2a6cdd6f9e4dce824b8208"},{"fixed":"04f5bbedee58c538934374dc45182d8fc5926fa3"}],"database_specific":{"versions":[{"introduced":"4.2.0"},{"fixed":"4.3.3"}]}}],"versions":["v4.2.0","v4.2.1","v4.2.2","v4.2.3","v4.2.4","v4.2.5","v4.3.0","v4.3.1","v4.3.2"],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2021-20235.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H"}]}