You could easily store KeePass database files on a network share. Create one file per access group, for instance. KeePass works pretty well with multiple database files (it has a simple tabbed interface when you do so and you can do things like color code the icons in the tabs). You can use network share permissions to make the database files read-only to particular users and KeePass will do the right thing with read-only files (mark it as read-only in the UI and disallow editing actions).