The capability check to access other badges in Moodle 3.0 through 3.0.3, 2.9 through 2.9.5, 2.8 through 2.8.11, 2.7 through 2.7.13, and earlier allows remote authenticated users to read the badges of other users.
https://bugzilla.redhat.com/show_bug.cgi?id=1335933