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 how the application parses font names embedded within an atom. When parsing the font name, the application will treat a length from the file as a signed value when copying font data into a buffer. Due to an unsigned promotion, this can be used to write outside the bounds of a buffer which can lead to code execution under the context of the application.