static void handle_binary_protocol_error(conn *c) {
    write_bin_error(c, PROTOCOL_BINARY_RESPONSE_EINVAL, 0);
    if (settings.verbose) {
        fprintf(stderr, "Protocol error (opcode %02x), close connection %d\n",
                c->binary_header.request.opcode, c->sfd);
    }
    c->write_and_go = conn_closing;
}

The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.