Apple today released a bevy of patches that, by my quick count, fix about 55 bugs in its flagship OS X operating system as well as Java. Fortunately, through Software Update, the patch updates for Java for Mac OS X 19.5 Update 3, and Security UPdate 2009-001, which total 47 MB, went smoothly for this user.While the patches fix nearly 50 security holes, including a number in Java for OS X 10.5 and many of the open source components that provide some of the underbelly of the operating system, it's the Safari RSS flaw that is perhaps the most dangerous to the greatest number of users:
CVE-ID: CVE-2009-0137 Available for: Mac OS X v10.4.11, Mac OS X Server v10.4.11, Mac OS X v10.5.6, Mac OS X Server v10.5.6
Impact: Accessing a maliciously crafted feed: URL may lead to arbitrary code execution
Looks like just visiting a maliciously crafted Web site is all that would be needed to nail your system.
More information about the update is available from Apple, right here.
If you haven't yet, run Software Update. Despite the number of fixes, it only took a few minutes for me to patch a Mac Pro and a MacBook Pro.