{"id":"CVE-2020-15133","aliases":["GHSA-2v5c-755p-p4gv"],"url":"https://o3.security/vulnerability/CVE-2020-15133","summary":"Missing TLS certificate verification in faye-websocket","details":"In faye-websocket before version 0.11.0, there is a lack of certification validation in TLS handshakes. The `Faye::WebSocket::Client` class uses the `EM::Connection#start_tls` method in EventMachine to implement the TLS handshake whenever a `wss:` URL is used for the connection. This method does not implement certificate verification by default, meaning that it does not check that the server presents a valid and trusted TLS certificate for the expected hostname. That means that any `wss:` connection made using this library is vulnerable to a man-in-the-middle attack, since it does not confirm the identity of the server it is connected to. For further background information on this issue, please see the referenced GitHub Advisory. Upgrading `faye-websocket` to v0.11.0 is recommended.","published":"2020-07-31T18:15:14.473Z","modified":"2026-07-09T00:22:36.930773Z","cvss":{"score":8.7,"severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:N"},"epss":null,"cisaKev":null,"exploitsKnown":null,"affectedPackages":[{"ecosystem":"RubyGems","name":"faye-websocket","fixedVersion":"0.11.0"}],"fix":null,"references":[{"type":"EVIDENCE","url":"https://blog.jcoglan.com/2020/07/31/missing-tls-verification-in-faye/"},{"type":"EVIDENCE","url":"https://github.com/faye/faye-websocket-ruby/security/advisories/GHSA-2v5c-755p-p4gv"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-07-09T00:22:36.930773Z"}}