Apple today released Security Update 2006-004 which is recommended for all Mac Pro systems running Mac OS X v10.4.7 (build 8K1079), and systems running Mac OS X Server v10.4.7 (Universal), and improves the security of the following components:
• ImageIO
• OpenSSH
The update is available via Software Update and also as a standalone installer.
More info and download link (2.3MB) here.