Screaming Penguin - Source Does Matter

See the linked advisory, just about all Linux distros (and many other systems/devices) run OpenSSH and all versions prior to 3.7.1 (which was just released) are vulnerable to a buffer management issue that enables a DoS attack and "could allow an attacker to execute arbitrary code". See the linked CERT advisory for more info.   Advisory CA-2003-24 Buffer Management Vulnerability in OpenSSH