This vulnerability allows remote attackers to execute arbitrary code on vulnerable installations of Apple Quicktime. User interaction is required to exploit this vulnerability in that the target must visit a malicious page or open a malicious file.
The specific flaw exists within the way Quicktime handles the 'trun' atom. Quicktime uses user supplied data in the 'sampleCount' field to calculate a buffer size. An integer wrap can occur that results in the allocation of a memory buffer that is smaller than intended. When Quicktime writes to this buffer it causes a memory corruption that can lead to remote code execution under the context of the current user.