Firefox 1.0 allows remote attackers to modify Boolean configuration parameters for the about:config site by using a plugin such as Flash, and the -moz-opacity filter, to display the about:config site then cause the user to double-click at a certain screen position, aka "Fireflashing."
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A10967
https://exchange.xforce.ibmcloud.com/vulnerabilities/19266
https://bugzilla.mozilla.org/show_bug.cgi?id=280664
http://www.redhat.com/support/errata/RHSA-2005-384.html
http://www.redhat.com/support/errata/RHSA-2005-323.html
http://www.redhat.com/support/errata/RHSA-2005-176.html
http://www.novell.com/linux/security/advisories/2005_16_mozilla_firefox.html
http://www.mozilla.org/security/announce/mfsa2005-27.html
http://www.gentoo.org/security/en/glsa/glsa-200503-30.xml