What are the potential pitfalls of using $_GET in PHP for processing user input?

Using $_GET for processing user input can lead to security vulnerabilities such as SQL injection attacks or cross-site scripting (XSS) attacks if the input is not properly sanitized or validated. To mitigate these risks, always sanitize and validate user input before using it in your application.

// Example of sanitizing user input from $_GET
$user_input = isset($_GET['input']) ? htmlspecialchars($_GET['input']) : '';