A command bus is the operational path that carries authorized instructions from an operator console or control service to the systems being managed. In mission software, it is the channel that turns a user action into an actual device or spacecraft command, so it is part of the control plane rather than just the user interface.
In cyber security, the command bus matters because any weakness that exposes it can affect integrity, not just confidentiality. If an attacker can reach this path through broken authentication, poor session handling, or flawed authorization, they may be able to submit arbitrary commands, alter state, or disrupt operations. Defenders protect command buses with strong authentication, strict role checks, network isolation, command signing or approval workflows, and detailed logging of every issued command. Monitoring the bus helps detect abuse quickly and limits the impact of compromised web consoles or operator tools.