Apple is recommending that QuickTime users download its update for Version 7.1.6 to fix a pair of security glitches.
One of the first two problems, in QuickTime for Java, can lead users to having their systems hijacked if they visit a malicious site. If a user visits a site containing a maliciously crafted Java applet, an attacker can trigger the vulnerability and take over the target system. The second glitch, like the first, a user has to visit a site with a maliciously crafted Java applet. The attacker can take advantage of the vulnerability and may be able to read sensitive information off your system.
See our How To for steps in installing QuickTime 7.1.6.http://ict.cas.psu.edu/training/howto/util/QuickTimeInstall.htm