What are common pitfalls when using PHP to handle user input?

One common pitfall when handling user input in PHP is not properly sanitizing and validating the data, 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 using it in your application. 

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

// Sanitize the input to remove any potentially harmful characters
$sanitizedInput = filter_var($userInput, FILTER_SANITIZE_STRING);

// Validate the input to ensure it meets certain criteria (e.g. minimum length)
if(strlen($sanitizedInput) >= 5) {
    // Proceed with using the sanitized input
    // Your code here
} else {
    // Handle validation error
    echo "Input must be at least 5 characters long.";
}

Keywords

SQL injection cross-site scripting (XSS) input validation htmlspecialchars filter_input

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