Firefox before 1.0.2 allows remote attackers to execute arbitrary code by tricking a user into saving a page as a Firefox sidebar panel, then using the sidebar panel to inject Javascript into a privileged page.
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A11868
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A100027
https://bugzilla.mozilla.org/show_bug.cgi?id=284627
http://www.vupen.com/english/advisories/2005/0296
http://www.redhat.com/support/errata/RHSA-2005-336.html