Cerbos and .NET Core Identity: where RBAC starts to break

TL;DR: Hard-coded role and claims checks become brittle as .NET Core applications need ownership, context, and dynamic policy decisions, according to Cerbos. Moving authorization into external policies reduces code-level sprawl and makes access control easier to change without rewriting controllers.

NHIMG editorial — based on content published by Cerbos: integrating Cerbos with .NET Core Identity for policy-driven authorization

Questions worth separating out

Q: How should security teams handle contextual authorization in .NET Core applications?

A: Use authentication for identity verification and externalize authorization into a governed policy layer that can evaluate resource attributes such as ownership, status, or tenant context.

Q: When does role-based access control become a poor fit for application security?

A: RBAC becomes a poor fit when access depends on more than a stable job role, such as document ownership, publication state, or time-bound business rules.

Q: What should teams do to keep authorization changes from becoming code debt?

A: Move changing access rules into version-controlled policy files, then test those policies independently of the application release cycle.

Practitioner guidance

• Separate authentication from authorization decisions Keep .NET Core Identity for sign-in and identity proofing, but route authorization through a dedicated policy service so access rules do not accumulate inside controllers.
• Pass resource attributes explicitly to the decision point Include ownership, publication state, and other resource attributes in every authorization request so rules can be evaluated consistently outside application code.
• Version and test policy files like application code Store policy YAML in source control, run compile checks in CI, and review changes through the same change-control process used for code releases.

What's in the full article

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

• Step-by-step .NET Core implementation details for custom authorization providers and handlers.
• Full Cerbos policy examples for document ownership, publication state, and admin override logic.
• Local Docker setup and compile validation steps for testing policy changes during development.
• End-to-end request flow showing how the authorization service evaluates principals and resource attributes.

👉 Read Cerbos' guide to policy-driven authorization with .NET Core Identity →

Cerbos and .NET Core Identity: where RBAC starts to break?

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