What are some potential pitfalls of relying on the HTTP_REFERER value in PHP scripts?

Relying on the HTTP_REFERER value in PHP scripts can be risky as 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 any data coming from the HTTP_REFERER header before using it in your scripts. 

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

// Validate and sanitize the referer URL
if (filter_var($referer, FILTER_VALIDATE_URL)) {
    // Proceed with using the referer URL in your script
} else {
    // Handle the invalid referer URL
}

Keywords

HTTP_REFERER security vulnerability data validation user input cross-site scripting

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