What potential issue may arise when using $_POST variables in PHP forms?

One potential issue when using $_POST variables in PHP forms is the vulnerability to cross-site scripting (XSS) attacks. To prevent this, you should always sanitize and validate user input before using it in your application. This can be done by using functions like htmlspecialchars() to escape special characters and prevent malicious scripts from being executed. 

// Sanitize and validate user input from a form
if(isset($_POST['input_field'])){
    $input = htmlspecialchars($_POST['input_field']);
    
    // Use the sanitized input in your application
    // For example, store it in a database or display it on a webpage
}

Keywords

$_POST variables security vulnerabilities SQL injection cross-site scripting data validation

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