CVE-2026-55953 TLS 1.2 and DTLS client accepts unoffered anonymous cipher suite, bypassing server authentication

The Erlang/OTP ssl TLS 1.2 and earlier and DTLS client does not verify that the cipher suite selected by the server in ServerHello was among the suites offered by the client in ClientHello. The client-side tlshandshake:hello/5 handler validates the negotiated protocol version and the downgrade...

CVE-2026-55953

Summary: CVE-2026-55953 affects Erlang/OTP SSL/TLS client when using TLS 1.2 and DTLS. The client fails to verify that the server-chosen cipher suite in ServerHello was among the suites offered in ClientHello. An on-path attacker can respond with a ServerHello using an anonymous cipher suite (e.g...