The cert_TestHostName function in Mozilla before 1.7, Firefox before 0.9, and Thunderbird before 0.7, only checks the hostname portion of a certificate when the hostname portion of the URI is not a fully qualified domain name (FQDN), which allows remote attackers to spoof trusted certificates.
Mozilla (Suite) before 1.7.1, Firefox before 0.9.2, and Thunderbird before 0.7.2 allow remote attackers to launch arbitrary programs via a URI referencing the shell: protocol.
Netscape Navigator 7.0.2 and Mozilla allows remote attackers to access cookie information in a different domain via an HTTP request for a domain with an extra . (dot) at the end.