Firefox 2.0.0.6 under MacOS 10.4.10, the links result in an alert saying You are attempting to login to site mozilla.org with username chrome%20javascript but the site does not require authentication. Ths may be an attempt to trick you. Is that the site you really want to visit? (I’m paraphrasing the alert warning from memory)
Even if I do click Yes on that alert then Firefox tries to open a URL on http://mozilla.org, not a local file or chrome type URL or whatever you are trying to do as an exploit, and all that results is a 404 file not found.
So it appears that Firefox on the Mac is not vulnerable to this after all.