fix(cgi-bin): add login cookie guard to set_membership

cgi-bin/set_membership

@@ -166,6 +166,15 @@ if (not $anvil->data->{sys}{database}{connections})
 	$anvil->nice_exit({exit_code => 1});
 }
 
+my $cookie_problem = $anvil->Account->read_cookies();
+
+# Don't do anything data-related if the user is not logged in.
+if ($cookie_problem)
+{
+	$anvil->Log->entry({ source => $THIS_FILE, line => __LINE__, level => 0, 'print' => 1, priority => "err", key => "error_0307" });
+	$anvil->nice_exit({ exit_code => 1 });
+}
+
 # Read in any CGI variables, if needed.
 $anvil->Get->cgi();