Are there any potential pitfalls or limitations to relying on the HTTP_REFERER header in PHP?

One potential pitfall of relying on the HTTP_REFERER header in PHP is that it can be easily spoofed or manipulated by the user. This can lead to security vulnerabilities such as CSRF attacks. To mitigate this risk, it is recommended to validate and sanitize the HTTP_REFERER header before using it in your application. 

$referer = isset($_SERVER['HTTP_REFERER']) ? $_SERVER['HTTP_REFERER'] : '';

// Validate and sanitize the HTTP_REFERER header
if(filter_var($referer, FILTER_VALIDATE_URL)) {
    // Proceed with using the HTTP_REFERER header
} else {
    // Handle invalid or malicious HTTP_REFERER header
}

Keywords

HTTP_REFERER header security vulnerabilities validation

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