Authentication vs authorization: where application controls go wrong

TL;DR: Authentication verifies who a user or process is, while authorization determines what that identity can do, according to Cerbos. The distinction matters because weak identity verification or coarse permissioning can each leave sensitive application resources exposed, even when both controls are present.

NHIMG editorial — based on content published by Cerbos: authentication vs authorization in application security

Questions worth separating out

Q: How should security teams design authorization so it does not depend on fragile role sprawl?

A: Use roles for stable access patterns and move exceptions, temporary access, and context-sensitive decisions into attribute-based or policy-driven controls.

Q: Why do authentication controls fail to protect applications when authorization is too broad?

A: Authentication only proves identity, it does not limit what that identity can do.

Q: How can teams tell whether their authorization model is actually working?

A: Look for evidence that permissions match intended business purpose, are reviewable, and can be revoked without side effects.

Practitioner guidance

• Map identity subject types before writing policy Separate humans, service accounts, API keys, and other non-human identities in your authorization design so the same rule does not get reused across different lifecycle patterns.
• Review role sprawl in high-risk applications Identify roles that exist only to handle exceptions or temporary access, then decide whether they should become time-bound entitlements or attribute-driven policies.
• Test permission boundaries independently of login success Validate what authenticated identities can actually reach after login, including admin paths, service endpoints, and delegated actions that may sit outside the normal user journey.

What's in the full article

Cerbos's full article covers the implementation detail this post intentionally leaves for the source:

• Concrete examples of username-password, MFA, and biometric authentication flows in application design.
• A more detailed comparison of RBAC and ABAC for application authorization decisions.
• The article's own framing of why teams build in-house authorization logic and where that becomes difficult to maintain.
• Cerbos's explanation of how authorization-as-a-service changes implementation responsibility.

👉 Read Cerbos's explanation of authentication and authorization →

Authentication vs authorization: where application controls go wrong?

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