QuickTime 7.6.7 has now been released [URL] ; and Secunia's PSI has removed this vulnerability from its listed of (In)Secure Browsing.  
The following has been copied/pasted from [URL] DescriptionKrystian Kloskowski has discovered a [highly critical] vulnerability in QuickTime Player, which can be exploited by malicious people to compromise a user's system.The vulnerability is caused due to a boundary error in QuickTimeStreaming.qtx when constructing a string to write to a debug log file. This can be exploited to cause a stack-based buffer overflow by e.g. tricking a user into viewing a specially crafted web page that references a SMIL file containing an overly long URL.Successful exploitation allows execution of arbitrary code.The vulnerability is confirmed in version 7.6.6 (1671) for Windows. Other versions may also be affected. [NO] SolutionA patch or updated version is not currently available. EDIT:   By virtue of this QuickTime vulnerability, Secunia is now reporting all my browswers (IE, FF, Opera) as being insecure.  
Now PATCHED: QuickTime Player Streaming Debug Error Logging Buffer Overflow