Most overlay networks are highly decentralized and self-organized. Therefore, vertex cutset often exists in such systems due to the lack of centralized management. Vertex cutset is defined as a minimum number set of vertices whose removal increases the number of components. In this paper, we propose a distributed mechanism which efficiently detects the vertex cutset with 1 or 2 vertices and neutralize them into normal nodes with slight overhead. We prove the correctness of this algorithm and evaluate the performance of our design through trace driven simulations. The results show that our algorithm greatly improves the reliability of an overlay network upon the failure of vertex cutset.