Laravel 5 - Recover SESSION for PGRFileManager.php

Please, with my PGRFileManager.php (with my ckeditor),
The visitors can unfortunately access to file to this adress :
http://my-web-site.com/ckeditor/plugins/pgrfilemanager/PGRFileManager.php

To secure I want to ensure that if it is not a user of my admin, redirect (exit) the visitor ...

At Login I create a new SESSION "usercms" :

public function postLogin(Request $request)
{
	$login = Auth::attempt([

							'username' => $request->input('username'),
							'password' => $request->input('password')
						], $request->input('remember'));

	if ($login) {
		Session::put('usercms', 'EXISTE');  // CREATE SESSION
		...
	}
}


	

OK.
_But the prolem, in my PGRFileManager.php, with this code :

session_start();
var_dump($_SESSION['usercms']);

Wamp return this error :
"Notice: Undefined index: usercms in C:\wamp\www___Laravel\my-web-site\ckeditor\plugins\pgrfilemanager\PGRFileManager.php on line 4"

What is the solution please?
Thank You.