Apple has posted a Security Update labelled 2007-001. It is described as below:

Security Update 2007-001 is recommended for all users and improves the security of the following components:

QuickTime

For detailed information on this update, please visit this website: http://docs.info.apple.com/article.html?artnum=61798

The update weights 5.9MB and is available either through the Software Update utility or through Apple's support web site.