toolkit/components/passwordmgr/src/nsLoginManagerPrompter.js in the asynchronous Authorization Prompt implementation in Mozilla Firefox 3.6 before 3.6.2 does not properly handle concurrent authorization requests from multiple web sites, which might allow remote web servers to spoof an authorization dialog and capture credentials by demanding HTTP authentication in opportunistic circumstances.
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A8281
https://bugzilla.mozilla.org/show_bug.cgi?id=537862
http://www.vupen.com/english/advisories/2010/0692
http://www.securityfocus.com/bid/38918
http://www.mozilla.org/security/announce/2010/mfsa2010-15.html
http://www.mandriva.com/security/advisories?name=MDVSA-2010:070