Authconfig version 6.2.8 is vulnerable to an Information exposure while using SSSD to authenticate against remote server resulting in the leak of information about existing usernames.
https://pagure.io/authconfig/c/0972f61ad4b5657ed89cf953e8f58f6513096224?branch=master
https://bugzilla.redhat.com/show_bug.cgi?id=1441604