tag/user.php in Moodle through 2.5.9, 2.6.x before 2.6.9, 2.7.x before 2.7.6, and 2.8.x before 2.8.4 does not consider the moodle/tag:flag capability before proceeding with a flaginappropriate action, which allows remote authenticated users to bypass intended access restrictions via the "Flag as inappropriate" feature.