The ABB IDAL HTTP server is vulnerable to a buffer overflow when a long Host header is sent in a web request. The Host header value overflows a buffer and overwrites a Structured Exception Handler (SEH) address. An unauthenticated attacker can submit a Host header value of 2047 bytes or more to overflow the buffer and overwrite the SEH address, which can then be leveraged to execute attacker-controlled code on the server.