Mozilla Firefox before 17.0 Firefox ESR 10.x before 10.0.11 Thunderbird before 17.0 Thunderbird ESR 10.x before 10.0.11 and SeaMonkey before 2.14 implement cross-origin wrappers with a filtering behavior that does not properly restrict write actions which allows remote attackers to conduct cross-site scripting (XSS) attacks via a crafted web site.