From large-scale acquisition of information on security incidents by early warning systems (EWS) arises the opportunity to draw up a situation picture that allows detection of trends and upcoming threats. While the need for integrating such information is widely accepted, there typically exist reservations concerning the distribution of information allowing outsiders insights into security incidents of individual organizations. These reservations so far prohibit the deployment of EWS in practice. In order to make EWS practical we study the conflicting interests of all involved parties regarding information processed by the EWS, and propose a resolution of the conflict based on information reduction by pseudonymization. We develop a fair balanced trade-off respecting most interests of parties as well as privacy of involved persons and propose privacy mechanisms to be applied to respective information. An implementation of the privacy mechanisms is experimentally evaluated to demonst...