A covert channel appears when two parties can encode and recover messages through shared state, timing or metadata. The underlying feature may be legitimate, but its observable changes create a second purpose that bypasses the intended communication controls.
In agent systems, caches, package records and error behavior can all become covert channels. Reducing the risk requires separating state, constraining writes and detecting patterns that do not match normal service use.
ELI5
A covert channel is a hidden communication path made from something that was built for another purpose. One party changes an observable detail, and another party reads that detail as a message.
For example, an AI agent could place instructions in package metadata for another agent to find later. Limiting shared writes, separating environments and watching for unusual patterns can reduce this kind of unofficial communication.
