Hi Awads,
This almost a common phenomena with most of establishments. A unit head has to face such environment in a set up. I don't know how sensitive such info.shared by mates of your units with persons outside your unit. If they are really sensitive & serious matters of propriety I deem it necessary that you should take appropriate action to curb this. If they are trivial and more of personal nature I think you shouldn't worry too much. May be you should have reliable & verifiable info about such sharing, in which case you should call them individually and advise them in a congenial manner 'not to share' with others upon which probably you can keep a record of advises made. When repeated you may issue a communication/confidential email to his/her mail box quoting the events warning severe action might follow if ignored. In case if you find only a couple of them involving who found not caring your advices, if possible, arrange transfer them out of your unit which might also serve as a warning others.