Impact: Visiting malicious websites may lead to arbitrary code execution
Description: A buffer overflow exists in QuickTime's handling of RTSP URLs. By enticing a user to access a maliciously-crafted RTSP URL, an attacker can trigger the buffer overflow, which may lead to arbitrary code execution. A QTL file that triggers this issue has been published on the Month of Apple Bugs web site (MOAB-01-01-2007). This update addresses the issue by performing additional validation of RTSP URLs.
As always, I recommend waiting a minimum of 72 hours before installing any software update.