title: php double extension vulnerability
body: <p>I am trying to learn more about file upload in PHP. I faced with a problem.
  I read some articles and watch some videos that hacker can attack with double extension however you check the file extension. like </p>
  
  <blockquote>
    <p>something.php.jpg</p>
  </blockquote>
  
  <p>How can it be prevented? Thank you in advance!</p>