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.