Microsoft Defender and Purview Add AI Agent Controls in September 2026
Microsoft's September 2026 security update delivers network-layer data loss prevention for agentic AI traffic, AI-generated email detonation summaries in Security Copilot, and enterprise-scale labelling automation in Microsoft Purview. These capabilities close a material gap for defenders by extending Zero Trust policy enforcement to on-behalf-of (OBO) agent actions — an emerging blind spot as autonomous agents operate across employee devices and cloud platforms. Residual gaps remain around coverage breadth for third-party agent frameworks, cross-platform policy portability, and the organisational maturity required to define reliable classification policies before enforcement becomes effective.