iOS 6.0.1 - safari doesn't allow me to login to this Apple forum

I'm using right now chrome since When I try to log in to this forum safari asks me for mail and psw but after this he simply turns into the homepage with the "sign in" option still there. Even if I put my credentials again the result is the same, no login made, no errors displayed and no way to start a discussion.

Is this just me or is a known bug for iOS 6?