takuhii: I'm not criticizing, I'm suggesting that perhaps it's a bad idea to "fix" the problem by opening up security holes.
A correct fix is coming soon. In the meantime, perhaps you should look at the actual source of the problem, which is, in this case, not the WordPress code, but the addon that your PHP is running which breaks the WordPress code.
First, check phpinfo() to see if you're running suhosin. If so, then you could, for example, try adding this to the top of your .htaccess file:
php_value suhosin.cookie.encrypt 0
That should disable the broken cookie encryption if you're running suhosin and having this issue. You may need to clear your browsers cookies afterwards and relogin and such.