Not for FreeBSD, but there is for OS X. Since we don't know the exact exploit used, we don't know if it works on Server too. This isn't as big as the difference between NT4 (server) and Windows 98 (client), but it's bigger than the difference between NT 3.51 Server and Workstation (the only difference there being registry entries that restricted Workstation, Microsoft made it a bit harder for NT 4 but it's still doable).
Face it, all OSs are a race against hackers. At any one time, any OS will have known and unknown vulnerabilities, patched and unpatched. What matters is the reaction time to fix once notified and the number/severity of the vulnerabilities for the roles you're using. Anything else is just playing games.