Separate Groups mode restrictions were not honored in the forum summary report, which would display users from other groups. This flaw affects versions 4.2 to 4.2.2, 4.1 to 4.1.5, 4.0 to 4.0.10, 3.11 to 3.11.16, 3.9 to 3.9.23 and earlier unsupported versions.
https://moodle.org/mod/forum/discuss.php?d=451592
Created moodle tracking bugs for this issue: Affects: epel-7 [bug 2244951] Affects: fedora-all [bug 2244952]