What potential pitfalls can arise when using sessions in PHP for Captcha validation?

Potential pitfalls that can arise when using sessions in PHP for Captcha validation include session hijacking, where an attacker steals the session data and uses it to bypass the Captcha, or session fixation, where an attacker sets the session ID before the Captcha is displayed. To mitigate these risks, regenerate the session ID after a successful Captcha validation to prevent session fixation attacks. 

// Start or resume session
session_start();

// Generate new session ID
session_regenerate_id();

// Validate Captcha
if ($_POST['captcha'] === $_SESSION['captcha']) {
    // Captcha validation successful
} else {
    // Captcha validation failed
}

Keywords

sessions PHP Captcha validation security session hijacking

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