Is there a function that allows a group of users to view only the data of their own group?
If you need a multitenant configuration it will be available in the new version CMDBuild 3.0, which will be released in March.
In the meantime (CMDBuild 2.5.1) you can still set permissions on a class, restricted by filters, so for each class each group can work only on their data.
CMDBuild Team