This question already has an answer here:
Please apologize my english.
In my website I use this kind of lines to define if the current user is an admin or a normal user:
<? if($_SESSION["nivel"] == 'administrator'){ ?>
I wanna know if this $_SESSION variable could be modified from client side by an user and cause me some security problems.
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$_SESSION is a superglobal which is only modified on the server.
Therefore the client will never be able to change it.