Mozilla Firefox before 16.0, Firefox ESR 10.x before 10.0.8, Thunderbird before 16.0, Thunderbird ESR 10.x before 10.0.8, and SeaMonkey before 2.13 do not properly manage history data, which allows remote attackers to conduct cross-site scripting (XSS) attacks or obtain sensitive POST content via vectors involving a location.hash write operation and history navigation that triggers the loading of a URL into the history object.