[eluser]Oscar Sosa[/eluser]
Actually the problem is that Input.php specifically on te line 217 is not taking into account the permited_uri_chars config parameter, why?, it appears to me a bug, so, you can change that line by this:
if ( ! preg_match("/^[" . config_item('permitted_uri_chars') . "]+$/i", $str))
And now you can add all your chars to that parameter and it will be taken into account.
In my case, I was having problems with ' and \, cause I send an array (ie I have one table grid with names like row[0][description]).
My english is not good enough cause I'm not an english spoken person, sorry XD
Bye!