Vulnerable v3.1 code example:
When the PHP mail() function processes this input, it interprets the \r\n sequence as a command to start a new line. The resulting email headers are reconstructed as: From: user@example.com Bcc: victim1@target.com Bcc: victim2@target.com php email form validation - v3.1 exploit
$mail = new PHPMailer(true); try $mail->setFrom('noreply@yourdomain.com', 'Contact Form'); $mail->addAddress('admin@yourdomain.com'); $mail->addReplyTo($validated_email, $validated_name); $mail->Subject = "Contact Form: " . $validated_name; $mail->Body = $validated_message; $mail->send(); catch (Exception $e) error_log("PHPMailer failed: " . $mail->ErrorInfo); Vulnerable v3
Systems using PHP-CGI on Windows are particularly vulnerable to similar argument injection flaws (e.g., CVE-2024-4577 ). The Core Vulnerability: Email Header Injection
(queue directory), an attacker can force the server to write a new PHP file (a "webshell") into the web root directory. Remote Execution
Understanding how these exploits work is essential for developers to secure their applications against modern threats. The Core Vulnerability: Email Header Injection