Many Apple Users complained started to complain on twitter, that iTunes Connect is logging them into someone else’s account. Some users got directly logged-in into others account, while some got while page refresh.
It caused serious issues like, showing apps of different users to other users, but when they tried to access those apps, they received error message sending them back to their own account.
iTunes Connect is has been officially taken down by Apple since the issue, and now what all users can see is Unavailable page. Hope this gets back up soon, as soon as Apple engineers get it back to normal.