Microsoft Says AI Agents Cannot Be Trusted and Could Become Insider Security Threats

Microsoft warns organizations to treat AI agents as potential insider risks not because they are automatically malicious, but because they can access company data, apps, and tools and act on that access at high speed.

The warning, published on October 19, 2026, comes as businesses use agents to handle tasks such as writing code, reviewing documents, and processing expenses.

An agent’s actions can change as its instructions, data, or working context change. It may make a mistake, follow harmful directions hidden in a document, or be compromised.

Because agents can act across connected systems, an unsafe action could expose sensitive information or change business records before a person notices. Microsoft’s point is not that every agent is dangerous. It is that organizations should not assume an agent will always behave as intended.

The risk grows when an agent receives more access than its task requires. An agent used to review expense claims, for example, may need…