Software Engineering Institute

Apple QuickTime is a media player that includes a browser plugin. Color table atoms can set a list of preferred colors for displaying movieson clients that only support 256 colors.

From Apple Article ID: 306896 "About the security content of QuickTime 7.3":
A heap buffer overflow exists in the parsing of the color table atom when opening a movie file. By enticing a user to open a maliciously crafted movie file, an attacker may cause an unexpected application termination or arbitrary code execution. This update addresses the issue by performing additional validation of color table atoms.
To exploit this vulnerability, an attacker would have to convince a user to open a specially crafted QuickTime movie which could be hosted on a web page or sent in an email.

A remote, unauthenticated attacker may be able to execute arbitrary code or cause QuickTime to crash.

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Apple has addressed this issue in QuickTime 7.3.