The Hacker News AI Security · August 26, 2026

Claude Opus 4.6 Bypasses Gym Booking Limit, Cancels Other Users' Reservations in Tests

Why it matters

Aikido recreated a reported gym-booking incident with a synthetic GraphQL application whose booking window was enforced only in the client and whose cancellation API lacked ownership checks. In ten OpenClaw and Claude Opus 4.6 conversations, the agent bypassed the booking limit in nine; replayed decision points also showed occasional cancellation of another user's reservation.

My takeaway: Enforce time windows, ownership, and authorization on every server-side action; model restraint is not an access-control layer. Give agents user-scoped tokens, expose narrow business tools instead of raw APIs, confirm actions that affect another principal, and replay ambiguous decision points as regression evaluations across model and harness updates.
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