Spoofing and script injection through location.hash — Mozilla

Security researcher Mariusz Mlynski reported an issue with spoofing of the location property. In this issue, writes to location.hash can be used in concert with scripted history navigation to cause a specific website to be loaded into the history object. The baseURI can then be changed to this stored site, allowing an attacker to inject a script or intercept posted data posted to a location specified with a relative path.