What are potential pitfalls when handling form submissions in PHP?

One potential pitfall when handling form submissions in PHP is not properly sanitizing and validating user input, which can lead to security vulnerabilities such as SQL injection or cross-site scripting attacks. To mitigate this risk, always sanitize and validate user input before processing it in your PHP script. 

// Example of sanitizing and validating user input in PHP form submission
if ($_SERVER["REQUEST_METHOD"] == "POST") {
    $username = htmlspecialchars($_POST['username']);
    $email = filter_var($_POST['email'], FILTER_VALIDATE_EMAIL);
    
    // Validate input
    if (empty($username) || empty($email)) {
        echo "Please fill out all fields.";
    } else {
        // Process form submission
        // Your code here
    }
}

Keywords

SQL injection cross-site scripting form validation CSRF protection error handling

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