Apple didn’t bother with getting things fixed that quickly, so Mozilla has jumped on the ball and updated Firefox to version 126.96.36.199 to fix the recent QuickTime vulnerability. If your Firefox hasn’t updated itself – then it should soon (or you can always go to Help > Check for Updates to get the latest Firefox version).
Need more? Here is a little more information about this issue and fix via Mozilla Developer News:
Due to the security fixes, we strongly recommend that all Firefox users upgrade to this latest release. If you are still running Firefox 1.5.0.x, you are highly encouraged to upgrade to the Firefox 2 series as Mozilla ceased supporting Firefox 1.5.0.x in May 2007. Simply choose “Check for Updates…” from the Help menu to begin the upgrade process.