What is the potential vulnerability 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. An attacker can manipulate the value of the PHP_SELF variable to inject malicious code into your form, leading to security vulnerabilities. To prevent this, 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">
    <!-- Form fields go here -->
</form>

Keywords

$_SERVER["PHP_SELF"] vulnerability PHP forms security injection

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