The Safari Mac OS X security leak, that brought researcher Dino Dai Zovi 10.000 dollars, maybe also dangerous for Windows users using Firefox. The exploit uses a Java based leak in QuickTime, and all browsers with this mediaplayer installed are known to be vulnerable.
“Firefox on Windows is considered a risk now. Safari and Firefox on the Mac OS are considered vulnerable”, according to Dai Zovi. Users that do not want to run any risks are advised not to run Java, or rather not to use QuickTime.