For reference: <http://news.cnet.com/8301-31921_3-20072755-281/dropbox-confirms-security-glitch-no-password-required/>. Can someone explain to me how this bug can happen if they properly tested this on a staging server with an identical environment to production? I'm trying to understand if it was just a random mistake that could happen to anyone, or if it was just negligence on their part. Thx in advance for any input!