Page load short-circuit can lead to XSS — Mozilla

Security researchers Jordi Chancel and Eddy Bordi reported that they could short-circuit page loads to show the address of a different site than what is loaded in the window in the addressbar. Security researcher Chris McGowen independently reported the same flaw, and further demonstrated that this could lead to loading scripts from the attacker’s site, leaving users vulnerable to cross-site scripting (XSS) attacks.