How can global variables in PHP, such as $_POST, impact the security and integrity of data processing in a web application?

Global variables in PHP, such as $_POST, can impact the security and integrity of data processing in a web application because they can be manipulated by users to inject malicious data or perform unauthorized actions. To mitigate this risk, it is important to sanitize and validate all user input before processing it further in the application. 

// Example of sanitizing and validating user input from $_POST
$username = isset($_POST['username']) ? htmlspecialchars($_POST['username']) : '';
$password = isset($_POST['password']) ? htmlspecialchars($_POST['password']) : '';

// Validate input
if (!empty($username) && !empty($password)) {
    // Process the input further
} else {
    // Handle invalid input
}

Keywords

global variables $_POST security data processing web application

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