-Quote taken from here: http://www.theregister.co.uk/2006/11/23/fake_login_flaw/
The latest versions of both Firefox and Internet Explorer are vulnerable to an unpatched flaw that allows hackers to snaffle users' login credentials via automated phishing attacks.
The information disclosure bug affects the password manager in Firefox 2.0 and its equivalent in IE7. Firefox's Password Manager, for example, fails to properly check URLs before filling in saved user credentials into web forms. As a result, hackers might be able to swipe users credentials via malicious forms in the same domain, providing users have already filled out forms on this domain.
It seems that firefox 2 is hit harder than IE7 because of the way Firefox automatically fills in the request forms once the page is viewed or if the user inputs a username help in the password manager cache.
For now it looks like the best thing to do is turn of your browsers password manager and fill in the form yourself...... but being security conscious we all do this anyway.....don't we ;)
For more info visit the following link as it details both Cross-Site Request Forgery and the newer Reverse Cross-Site Request vulnerability. This link below is also available on the above link's page as well.