What potential security risks can arise from not using htmlentities() in PHP form fields?

Not using htmlentities() in PHP form fields can leave your application vulnerable to cross-site scripting (XSS) attacks, where malicious scripts are injected into the webpage. This can lead to unauthorized access to sensitive data or manipulation of the webpage content. To prevent this, always use htmlentities() to encode user input before displaying it on the webpage.

// Using htmlentities() to encode user input before displaying it on the webpage
$user_input = "<script>alert('XSS attack!');</script>";
$encoded_input = htmlentities($user_input);

echo $encoded_input;