What is a common pitfall when accessing form data in PHP, as highlighted in the forum thread?

A common pitfall when accessing form data in PHP is not properly sanitizing user input, which can lead to security vulnerabilities such as SQL injection or cross-site scripting attacks. To solve this issue, it is important to always sanitize and validate user input before using it in your application.

// Sanitize and validate form data
$username = htmlspecialchars($_POST['username']);
$email = filter_var($_POST['email'], FILTER_SANITIZE_EMAIL);
$password = password_hash($_POST['password'], PASSWORD_DEFAULT);