What are the potential security risks associated with allowing unrestricted text input in PHP applications?

Allowing unrestricted text input in PHP applications can lead to various security risks such as SQL injection, cross-site scripting (XSS) attacks, and code injection. To mitigate these risks, it is essential to properly sanitize and validate user input before using it in your application.

// Example of sanitizing user input using the htmlspecialchars function
$user_input = $_POST['user_input'];
$clean_input = htmlspecialchars($user_input);