AI agent skill · by @Archive228

Authz Check

Verify that an endpoint checks ownership, not just authentication. Use on any handler that reads or mutates user data.

Archived 2026-10-23 · Source updated 2026-07-14 · License: MIT. Check the original repository for the latest version.

SKILL.md instructions

# Authz Check
The most common security hole: the code checks you're logged IN, but not that you OWN the thing.
- For every resource access: does it verify the current user is allowed THIS specific record? `WHERE id = ? AND owner_id = current_user` — not just `WHERE id = ?`.
- IDOR test: swap the ID in the request to another user's. Does it leak/allow?
- Admin/privileged actions: is the role checked server-side, every time, not just hidden in the UI?
- Default deny: new endpoints should require explicit authorization, not be open by oversight.
Output each handler that authenticates but doesn't authorize, with the missing check.