When redirecting using
header("Location MyPage.php"); in PHP, any code present after will be executed. So, if you're using this as a way to avoid user accessing pages where they should be logged in, the content of the page will still be processed and sent to the client. Using a proxy, you can set that despite returning a 302 error code, you'll also get the content of the page.
My question is, what other languages or framework have this issue ?