'The default configuration of OpenSSH through 6.1 enforces a fixed time limit between establishing a TCP connection and completing a login, which makes it easier for remote attackers to cause a denial of service (connection-slot exhaustion) by periodically making many new TCP connections.'
Mitigated with active Intrusion Prevention enabled.
While this DoS issue can affect ClearOS, the risk is low to the system with Intrusion Prevention services running and active updates of the Intrusion Prevention systems which watch for repetitive connections and block attempts.
Install, enable and subscribe to Intrusion Prevention and Intrusion Prevention updates.