We've built Cribber with privacy in mind. However, when you send a bulletin to your users they will have access to the content.
We've built restrictions into our mobile apps on how this content can be viewed. But, there will always be ways for users to share this information if they wish. Much like an employee could forward a company email to others, or someone could take and share photos of company documents.
Your workplace rules should apply to the user of Cribber and include guidance on sharing and disclosure of company and workplace information.