Earlier this week, news of a fairly dangerous flaw that occurred when combining Firefox and Quicktime was made public. The flaw was fairly severe, earning a "Critical" rating just about everywhere it was reported.
The Mozilla team has worked fast, however, and this evening released an update. Version 188.8.131.52 of the browser has been made available, solely to fix the QuickTime flaw. If you are using Firefox and haven't been auto-updated already, get yourself the update and surf merrily.