Php Email Form Validation - V3.1 Exploit Work

mail($to, $subject, 'Hello World!', $headers);

In several "v3.1" scripts, the application fails to sanitize the email parameter before echoing it back in a "thank you" or "error" page. php email form validation - v3.1 exploit

The exploit leverages the 5th parameter of the PHP mail() function, $additional_parameters , which passes flags directly to the system's sendmail binary. mail($to, $subject, 'Hello World