How should variables from a form be handled to prevent security vulnerabilities in PHP?

To prevent security vulnerabilities in PHP when handling variables from a form, it is important to sanitize and validate user input to prevent SQL injection, cross-site scripting (XSS), and other types of attacks. One way to do this is by using functions like filter_input() or htmlentities() to sanitize input and ensure that only expected data types and formats are accepted. 

// Example of sanitizing and validating form input in PHP
$name = filter_input(INPUT_POST, 'name', FILTER_SANITIZE_STRING);
$email = filter_input(INPUT_POST, 'email', FILTER_VALIDATE_EMAIL);

if ($name && $email) {
    // Process the form data securely
} else {
    // Handle validation errors
}

Keywords

SQL injection cross-site scripting htmlspecialchars prepared statements input validation

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