CVE-2011-2726

An access bypass issue was found in Drupal 7.x before version 7.5. If a Drupal site has the ability to attach File upload fields to any entity type in the system or has the ability to point individual File upload fields to the private file directory in comments, and the parent node is denied access, non-privileged users can still download the file attached to the comment if they know or guess its direct URL.

Source: CVE-2011-2726