What potential issues can arise from using the $HTTP_POST_VARS superglobal in PHP?

Using the $HTTP_POST_VARS superglobal in PHP can lead to security vulnerabilities as it is not recommended to directly access user input data in this way. It is better to use the $_POST superglobal array instead, as it provides the same functionality but is more secure.

// Using $_POST superglobal instead of $HTTP_POST_VARS
$value = $_POST['input_name'];