AI gateway authorization: what IAM teams are missing now

TL;DR: AI gateways can authenticate users and route traffic, but they often cannot decide what those identities may do across models, tools, MCP methods, and delegated agent calls, according to Cerbos. Fine-grained authorization shifts that decision to policy, where contextual access can be enforced at every hop instead of drifting into agent logic.

NHIMG editorial — based on content published by Cerbos: AI gateway authorization and fine-grained policy for models, tools, and agents

Questions worth separating out

Q: How should security teams govern AI gateway authorization across models, tools, and agents?

A: Use the gateway as the enforcement point, but evaluate every request against contextual policy before it reaches the model or tool.

Q: Why do AI gateways create governance gaps for IAM and PAM teams?

A: They verify identity at the edge, but they often do not decide whether that identity may use a model, tool, or downstream service in a specific business context.

Q: What breaks when agent-to-agent delegation is not attenuated?

A: The delegated agent can inherit more authority than the original task justified, especially if tokens are passed downstream unchanged.

Practitioner guidance

• Move authorisation decisions out of agent code Keep allow and deny logic in a central policy layer that the gateway can call before routing each AI request.
• Enforce attenuation on every delegated hop Require each sub-agent grant to be a strict subset of the delegator’s authority and the originating user’s permissions.
• Filter MCP tool discovery by principal and context Return a reduced tool catalog to low-privilege callers and reserve destructive methods for explicit break-glass roles.

What's in the full article

Cerbos's full guide covers the operational detail this post intentionally leaves for the source:

• Native enforcement patterns for AI gateways, including pre-request plugins, ext-auth calls, and SDK hooks.
• Concrete policy examples for model allowlists, data-residency routing, tool-level access, and bounded delegation.
• Context enrichment patterns that combine identity, resource, and relationship data at request time.
• Fail-closed design guidance for long-running or high-capability agent sessions.

👉 Read Cerbos's guide on AI gateway authorization and fine-grained policy →

AI gateway authorization: what IAM teams are missing now?

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