What are the potential security risks associated with allowing user input in PHP applications?

Allowing user input in PHP applications can lead to security risks such as SQL injection, cross-site scripting (XSS), and code injection attacks. To mitigate these risks, it is essential to sanitize and validate all user input before using it in the application. 

$user_input = $_POST['input'];

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

// Validate user input
if (preg_match("/^[a-zA-Z0-9]+$/", $clean_input)) {
    // Input is valid, proceed with using it in the application
} else {
    // Input is not valid, handle the error accordingly
}

Keywords

SQL injection Cross-site scripting (XSS) Remote code execution Input validation Escaping user input

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