What are some potential security risks associated with using $_SERVER['PHP_SELF'] in PHP forms?

Using $_SERVER['PHP_SELF'] in PHP forms can potentially expose your application to cross-site scripting (XSS) attacks. This is because the PHP_SELF variable can be manipulated by an attacker to inject malicious code into your form. To mitigate this risk, it is recommended to use htmlspecialchars() function to sanitize the PHP_SELF variable before using it in your form.

<form action="<?php echo htmlspecialchars($_SERVER['PHP_SELF']); ?>" method="post">