The installation confirmation dialog in Firefox before 1.0.1, Thunderbird before 1.0.1, and Mozilla before 1.7.6 allows remote attackers to use InstallTrigger to spoof the hostname of the host performing the installation via a long "user:pass" sequence in the URL, which appears before the real hostname.
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A10010
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A100041
https://bugzilla.mozilla.org/show_bug.cgi?id=268059
http://www.securityfocus.com/bid/12659
http://www.redhat.com/support/errata/RHSA-2005-384.html
http://www.redhat.com/support/errata/RHSA-2005-176.html
http://www.novell.com/linux/security/advisories/2006_04_25.html
http://www.mozilla.org/security/announce/mfsa2005-17.html
http://www.gentoo.org/security/en/glsa/glsa-200503-30.xml