Firefox 1.0 allows remote attackers to execute arbitrary code via plugins that load "privileged content" into frames, as demonstrated using certain XUL events when a user drags a scrollbar two times, aka "Firescrolling."
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A11772
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A100031
http://www.redhat.com/support/errata/RHSA-2005-384.html
http://www.redhat.com/support/errata/RHSA-2005-176.html
http://www.mozilla.org/security/announce/mfsa2005-27.html
http://www.gentoo.org/security/en/glsa/glsa-200503-30.xml