A method for using shared vulnerability to provide trusted communication services between systems is disclosed. For example, a server may deny access to a service which renders it vulnerable to an untrusted client unless access to a useful vulnerability is received from the client. That is, the server may trust the client because any misuse by the client may result in the server exploiting the shared vulnerability. A system may request access to a service on another system to perform some transaction. Upon receiving this request, the server may determine a vulnerability of the client useful in deterring or stopping unwanted actions. The server may request access to this vulnerability. Once this vulnerability has been granted to the server, the server may then grant access to the requested service to the client.