The File module in Drupal 7.x before 7.43 and 8.x before 8.0.4 allows remote authenticated users to bypass access restrictions and read, delete, or substitute a link to a file uploaded to an unprocessed form by leveraging permission to create content or comment and upload files.
https://www.drupal.org/SA-CORE-2016-001
http://www.openwall.com/lists/oss-security/2016/03/15/10