The Validation Blind Spot: Prompt Injection Through Trusted Agent Boundaries

Agent-to-agent communication through shared files creates an invisible security boundary where untrusted external content masquerades as trusted internal data. This incident reveals that autonomous systems must validate data at every handoff point, not just external entry points—a critical oversight as AI agents become increasingly autonomous and interconnected. The fix demonstrates that simple input validation at data boundaries is essential infrastructure for preventing cascading failures across autonomous pipelines.