From http://www.stepwise.com/Articles/Workbench/2001-12-17.01.html
"A serious security issue has been discovered in OpenSSH 3.0.2 (Apple ships this version with Mac OS X 10.1.3) update to the latest version as soon as possible."
The article goes on to describe how to install OpenSSH 3.1p1.
See also http://www.openbsd.org/advisories/ssh_channelalloc.txt
Mac OS X Hints
http://hints.macworld.com/article.php?story=20020307213048852