What potential issues can arise from including PHP code within a textarea input field?

Including PHP code within a textarea input field can pose security risks, as it allows users to execute arbitrary PHP code on the server. This can lead to potential vulnerabilities such as code injection attacks or unauthorized access to sensitive information. To prevent this, it is important to properly sanitize and validate user input before processing it.

// Sanitize and validate user input before processing
$input = $_POST['textarea_input'];
$sanitized_input = htmlspecialchars($input);
// Process the sanitized input further