What potential security risks are present in using register_globals = on in PHP?

Setting register_globals = on in PHP can lead to potential security risks such as variable injection attacks, where an attacker can manipulate variables in the script by setting values in the URL or form inputs. This can lead to unauthorized access to sensitive data or execution of malicious code. To mitigate this risk, it is recommended to set register_globals = off in the PHP configuration or manually initialize variables using $_GET, $_POST, or $_REQUEST superglobals.

// Set register_globals = off in php.ini configuration file

// Manually initialize variables using $_GET, $_POST, or $_REQUEST superglobals
$var1 = isset($_GET['var1']) ? $_GET['var1'] : '';
$var2 = isset($_POST['var2']) ? $_POST['var2'] : '';