Circular validation is a feedback loop in which the same system creates an artifact and then helps verify, justify, or explain that artifact. In security work, this can happen when an AI agent writes code, generates the tests for that code, and then produces the rationale that says the design is safe.
This matters because independent review is a core defense against bugs, misconfigurations, and hidden malicious behavior. If the generator also acts as the validator, errors can be reinforced instead of exposed, creating a false sense of assurance. Attackers benefit when teams trust fluent explanations more than evidence. Defenders reduce this risk by separating generation from verification, requiring human sign-off, using independent test suites and reviewers, and demanding traceable sources for design decisions. The goal is not to ban automation, but to prevent a system from becoming its own auditor.