Firefox 1.0.5 was released and fixes the following security vulnerabilities
MFSA 2005-56 Code execution through shared function objects
MFSA 2005-55 XHTML node spoofing
MFSA 2005-54 Javascript prompt origin spoofing
MFSA 2005-53 Standalone applications can run arbitrary code through the browser
MFSA 2005-52 Same origin violation: frame calling top.focus()
MFSA 2005-51 The return of frame-injection spoofing
MFSA 2005-50 Possibly exploitable crash in InstallVersion.compareTo()
MFSA 2005-49 Script injection from Firefox sidebar panel using data:
MFSA 2005-48 Same-origin violation with InstallTrigger callback
MFSA 2005-47 Code execution via "Set as Wallpaper"
MFSA 2005-46 XBL scripts ran even when Javascript disabled
MFSA 2005-45 Content-generated event vulnerabilities
The full reference list can be found
here along with descriptions of each security advisory and its potential threat level.