If you previously installed 3.6, I would update it to 3.6.2 NOW.
v.3.6.2, released March 22nd, 2010
Date: 3/22/2010 9:10 AM
Subject: I would hold off on a Firefox 3.6 deployment – a bug has been identified in version 3.6
A bug has been identified in Firefox 3.6.
All indications are that version 3.5.8 and older are not vulnerable. Only 3.6. Version 3.6.2 is scheduled to be released on March 30. I had two systems ask about auto downloading 3.6 so it seems they are pushing that version. This update push has probably since been rescinded.
Update: To clarify, as originally claimed this issue affects Firefox 3.6 only and not any earlier versions. Thunderbird and SeaMonkey are based on earlier versions of the browser engine and are not affected. People testing “3.7ÿ development builds should upgrade to 3.7 alpha 3 or the latest nightly build to ensure they have this fix.