These are the things according to the mozilla firefox site that were fixed in version 2.0.0.5:

MFSA 2007-25 XPCNativeWrapper pollution
MFSA 2007-24 Unauthorized access to wyciwyg:// documents
MFSA 2007-23 Remote code execution by launching Firefox from Internet Explorer
MFSA 2007-22 File type confusion due to %00 in name
MFSA 2007-21 Privilege escalation using an event handler attached to an element not in the document
MFSA 2007-20 Frame spoofing while window is loading
MFSA 2007-19 XSS using addEventListener and setTimeout
MFSA 2007-18 Crashes with evidence of memory corruption