This vulnerability allows 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 parsing of AVI files. When the AVI header contains a malformed nBlockAlign value in the _WAVEFORMATEX structure, a heap overflow may occur which can be leveraged to execute arbitrary code under the context of the current user.