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 do not prevent use of a \top\ frame name-attribute value to access the location property which makes it easier for remote attackers to conduct cross-site scripting (XSS) attacks via vectors involving a binary plugin.