{"id":"JLSEC-2026-516","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":"2026-05-20T04:15:03.557990351Z","published":"2026-05-20T04:02:19.667Z","upstream":["CVE-2021-20236"],"database_specific":{"sources":[{"html_url":"https://nvd.nist.gov/vuln/detail/CVE-2021-20236","published":"2021-05-28T11:15:07.933Z","database_specific":{"status":"Modified"},"imported":"2026-05-20T01:02:02.081Z","url":"https://services.nvd.nist.gov/rest/json/cves/2.0?cveId=CVE-2021-20236","modified":"2024-11-21T05:46:11.350Z","id":"CVE-2021-20236"}],"license":"CC-BY-4.0"},"references":[{"type":"WEB","url":"https://bugzilla.redhat.com/show_bug.cgi?id=1921976"},{"type":"WEB","url":"https://bugzilla.redhat.com/show_bug.cgi?id=1921976"},{"type":"WEB","url":"https://github.com/zeromq/libzmq/security/advisories/GHSA-qq65-x72m-9wr8"},{"type":"WEB","url":"https://github.com/zeromq/libzmq/security/advisories/GHSA-qq65-x72m-9wr8"}],"affected":[{"package":{"name":"ZeroMQ_jll","ecosystem":"Julia","purl":"pkg:julia/ZeroMQ_jll?uuid=8f1865be-045e-5c20-9c9f-bfbfb0764568"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"4.3.4+0"}]}],"database_specific":{"source":"https://github.com/JuliaLang/SecurityAdvisories.jl/tree/generated/osv/2026/JLSEC-2026-516.json"}}],"schema_version":"1.7.5"}