Apple released security updates that are a must install for administrators. The fixes address local and remote attacks that can occur in several applications including the following:
Address Book
AirPort
Automator
ICal
IChat
Parental Controls
Spaces
Time Machine
Voice Over
The core vulnerabilities in the fixes are AppKit code execution, Help Viewer buffer overflow vulnerability and CoreGraphics code execution vulnerability. These flaws could include Denial of Service Attacks (DOS) and elevation of privileges by an attacker. Administrators should backup their systems before the install.