The Plugin Finder Service (PFS) in Firefox before 1.0.3 allows remote attackers to execute arbitrary code via a javascript: URL in the PLUGINSPAGE attribute of an EMBED tag.
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A10279
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A100024
http://www.securityfocus.com/bid/13228
http://www.redhat.com/support/errata/RHSA-2005-383.html