What are the potential security risks of using PHP_SELF in a form action attribute?

Using PHP_SELF in a form action attribute can pose a security risk known as a cross-site scripting (XSS) attack. This is because PHP_SELF reflects the current script file name, which can be manipulated by an attacker to inject malicious code. To mitigate this risk, it is recommended to use htmlspecialchars() function to sanitize the PHP_SELF variable before using it in the form action attribute. 

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

Keywords

PHP_SELF form action attribute security risks cross-site scripting injection vulnerabilities

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