This major security threat has been acknowledged by Apple and is known to effect Safari on both Leopard and Windows. At this time Apple has not commented on when a fix will be released. The threat also extends further for OS X users by simply slicking a link in their mail, IMs, etc.
Fortunately Masternbrook listed out some simple steps you can take to protect yourself.
For OS X users other browsers like FireFox or Camino are safe to use. You can however fix Safari.
- Download and install the RCDefaultApp preference pane, following the included instructions.
- Open System Preferences and choose the Default Applications option.
- Select the "URLs" tab in the window that appears.
- Choose the "feed" URL type from the column on the left, and choose a different application or the "disabled" option.
- Repeat the previous step for the "feeds" and "feedsearch" URL types.
Windows users DO NOT USE SAFARI