What are the potential security risks of using external URLs for accessing a PHP login system?

Using external URLs for accessing a PHP login system can expose sensitive user information to potential security risks such as man-in-the-middle attacks, data interception, and session hijacking. To mitigate these risks, it is recommended to always use HTTPS for secure communication and avoid passing sensitive data in the URL parameters.

// Example of accessing a PHP login system using a secure internal URL
$login_url = "https://example.com/login.php";
header("Location: $login_url");
exit;