Summary Asynchronous message queuing middleware is a dependable solution for reliable communication in distributed computing environment. Soft System Bus (SSB) is an asynchronous messaging middleware that facilitates availability, reliability and continuity to SSB based Systems (SSBBSs). An SSBBS can be maintained, upgraded and reconfigured during run time without stopping its reactions even when it had some trouble or it is being attacked. A peer-to-peer (P2P) based implementation of an SSBBS was designed for large scale enterprise. However, the security analysis was not sufficient for P2P based SSBBSs. This paper gives a security analysis for P2P-based SSBBSs, and lists up security threats including new types of security threats for P2P-based SSBBSs. The paper also shows security requirements and technical issues for P2P-based SSBBSs