What are the advantages and disadvantages of using $_SERVER["HTTP_REFERER"] to determine parameter values in PHP scripts?

When using $_SERVER["HTTP_REFERER"] to determine parameter values in PHP scripts, the advantage is that it can provide information about the referring URL, which can be useful for tracking purposes. However, the disadvantage is that this information can be easily manipulated or spoofed by the user, leading to potential security vulnerabilities. It is recommended to validate and sanitize the input data before using it in the script to prevent any malicious attacks. 

// Validate and sanitize the HTTP_REFERER value before using it
$referer = isset($_SERVER["HTTP_REFERER"]) ? filter_var($_SERVER["HTTP_REFERER"], FILTER_VALIDATE_URL) : null;

if($referer) {
    // Use the sanitized $referer value in your script
    echo "Referring URL: " . $referer;
} else {
    echo "Invalid or missing referring URL";
}

Keywords

$_SERVER HTTP_REFERER parameter values advantages disadvantages

Related Questions