What are the potential security risks of including external content in PHP?

Including external content in PHP can pose security risks such as code injection, cross-site scripting (XSS), and remote file inclusion. To mitigate these risks, it is important to sanitize and validate any external content before including it in your PHP code. This can be done by using functions like htmlentities() to convert special characters to HTML entities and filter_var() to validate URLs.

// Sanitize and validate external content
$externalContent = filter_var($_GET['external_content'], FILTER_SANITIZE_STRING);

// Include the sanitized external content
include($externalContent);