This Node.js and Express compression middleware contains a memory leak. When a client aborts a connection while a compressed response is being transmitted, the zlib stream used for compression is not destroyed. A remote unauthenticated attacker can exploit this by repeatedly initiating requests and disconnecting prematurely, leading to the exhaustion of native zlib memory and causing the server to crash. This results in a Denial of Service (DoS), a condition where a service is unavailable to its intended users.