Haskell TLS library version 1.4.1 or earlier support SSL 2.0, SSL 3.0, TLS 1.0, TLS 1.1 and TLS 1.2. Here is brief summary of their security: SSL 2.0 is insecure and obsoleted by RFC 6176 SSL 3.0 is insecure and obsoleted by RFC 7568 TLS 1.0 is insecure due to lack of AEAD TLS 1.1 is insecure due to lack of AEAD TLS 1.2 is secure if it is used with proper parameters (using (EC)DHE and AEAD, disabl