Andreas Schneider reported that libssh2, a SSH2 client-side library, passes the number of bytes to a function that expects number of bits during the SSHv2 handshake when libssh2 is to get a suitable value for "group order" in the Diffie-Hellman negotiation. This weakens significantly the handshake security, potentially allowing an eavesdropper with enough resources to decrypt or intercept SSH sessions.