The specific flaw exists within the Quicktime.qts module responsible for parsing media files. While handling 3GP streams a function within this module a loop trusts a value directly from the media file and uses it during memory copy operations. By supplying a large enough value this buffer can be overflowed leading to arbitrary code execution under the context of the user accessing the file.
Patch Availability:
Apple has issued an update to correct this vulnerability.
More details can be found at: http://support.apple.com/kb/HT4447
