"Today, Mozilla made public bug #360493, which exposes Firefox's Password
Manager on many public sites. The flaw derives from Firefox's willingness to
supply the username and password stored on one page on a domain to another page
on a domain. For example, username/password input tags on a Myspace user's site
will be unhelpfully propagated with the visitor's Myspace.com credentials. It
was first discovered in the wild by Netcraft on Oct. 27. As this
proof-of-concept illustrates, because the username/password fields need not be
visible on the page, your password can be stolen in an almost completely
transparent fashion.
PoC here: http://www.info-svc.com/news/11-21-2006/rcsr1/
