General help

It's not SELinux. It's the other thing I use just to annoy you: nginx.

If you're using Nginx and PHP-FPM you need to add something to your config files to enable slash arguments.

Your location block that forwards PHP requests to PHP-FPM should look something like this:

    location ~ [^/]\.php(/|$) {
        fastcgi_split_path_info             ^(.+\.php)(/.+)$;
        fastcgi_index                       index.php;
        fastcgi_pass                        unix:/var/run/php-fpm/php-fpm.sock;
        include                             fastcgi_params;
        fastcgi_param      PATH_INFO        $fastcgi_path_info;
        fastcgi_param      SCRIPT_FILENAME  $document_root$fastcgi_script_name;
    }