Quicktime has a new update for version 7.1.6 to fix some flaws that could allow the bad guys to attack your computer. It is for both Mac and PC versions of Quicktime.
Description: A design issue exists in QuickTime for Java, which may allow a web browser's memory to be read by a Java applet. By enticing a user to visit a web page containing a maliciously crafted Java applet, an attacker can trigger the issue which may lead to the disclosure of sensitive information. This update addresses the issue by clearing memory before allowing it to be used by untrusted Java applets.More details on Apple's write up about it.
On a Mac, run Software Update and it will find the fix. On a PC, run Apple Software Update or visit the download page where you can gt the Windows version or the Mac one.