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AI Security

Interview question · Identity, OAuth & Access Control

What is a confused deputy, and how does it show up in agents and OAuth proxies?

A 1988 bug report that describes most agent incidents. The answer that scores turns it into a design rule: authority travels with the request.

mediumNewPreparation tags: Anthropic, OpenAI, MicrosoftUpdated Nov 2026

A 1988 bug report that describes most agent incidents. The answer that scores turns it into a design rule: authority travels with the request.

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What would you say before reading the answer?

  1. 01 State the assumptions your answer depends on.
  2. 02 Explain the mechanism and choose a control.
  3. 03 Name a condition that would change your decision.

The worked answer includes an approach, scoring criteria and follow-up questions. Compare the reasoning with your own.

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What if · the follow-ups in this answer

The answer works through 6 follow-ups like an interviewer would

A document conversion service fetches files from URLs and writes results to storage paths that callers specify, using its own credentials for both.

  1. What makes this a confused deputy?
  2. What if a caller supplies an internal URL?
  3. What if a caller supplies another customer's storage path?
  4. How does this appear in AI agents?
  5. How do tokens help?
  6. How would you fix the service?

Each rung has a nudge, a model answer, the principle that carries over and the weak answer to avoid. Sign in free to open it.

UP NEXT ON YOUR JOURNEY
Next in this trackHow do services authenticate to each other without long-lived secrets?Next in this trackWhy must a server reject tokens that were not issued for it, and what goes wrong with token passthrough?Next in this trackWalk through redirect URI validation, state, mix-up attacks, and what current OAuth security best practice requires.
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