Apple has released QuickTime 7.6.9 for Mac OS X 10.5.8 and Windows users. , QuickTime 7.6.9 addresses 15 security issues. The detail of the security update is available here at Apple's Support page.
QuickTime 7.6.9 for Windows can be downloaded from here.
UserAgent: Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.6; en-US; rv:22.214.171.124) Gecko/20101026 AlexaToolbar/alxf-2.0 Firefox/3.6.12