Vulnerability Discussion
The "root" group is a highly privileged group. Furthermore, the group-owner of this file should not have any access privileges anyway.
Check
Verify the group ownership of the "/boot/grub2/grub.cfg" file with the following command:
$ sudo stat -c "%G %n" /boot/grub2/grub.cfg
root /boot/grub2/grub.cfg
If "/boot/grub2/grub.cfg" file does not have a group owner of "root", this is a finding.
Fix
Change the group of the file /boot/grub2/grub.cfg to root by running the following command:
$ sudo chgrp root /boot/grub2/grub.cfg