What is the potential issue 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 scripts into your form. To solve this issue, it is recommended to use htmlspecialchars() function to escape any HTML characters before outputting the PHP_SELF variable in your form action attribute. 

<form action="<?php echo htmlspecialchars($_SERVER['PHP_SELF']); ?>" method="post">
    <!-- Form fields go here -->
</form>

Keywords

$_SERVER PHP_SELF forms security vulnerabilities

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