What are the common mistakes to avoid when handling user input data from HTML forms in PHP?

One common mistake to avoid when handling user input data from HTML forms in PHP is not properly sanitizing and validating the input. This can lead to security vulnerabilities such as SQL injection or cross-site scripting attacks. To solve this issue, always sanitize and validate user input before using it in your PHP code. 

// Example of properly sanitizing and validating user input
$user_input = $_POST['user_input'];

// Sanitize user input
$sanitized_input = filter_var($user_input, FILTER_SANITIZE_STRING);

// Validate user input
if (!empty($sanitized_input)) {
    // Proceed with using the sanitized input
    echo "User input: " . $sanitized_input;
} else {
    // Handle validation errors
    echo "Invalid input";
}

Keywords

SQL injection cross-site scripting validation sanitization htmlspecialchars

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