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Last updated: April 29, 2026
Every web app is a state machine. Order = pending → paid → shipped → delivered. State transitions have rules. The rules have gaps.
Every web app is a state machine. Order = pending → paid → shipped → delivered. State transitions have rules. The rules have gaps.
Attackers enumerate edges adversarially: can I go from pending to delivered, skipping paid? Can I cancel after shipped? Can I trigger paid → paid (double payment processing)?
The mindset: draw the state machine. For every state pair, ask “can the user force this transition?” The unintended yes-es are the bugs.
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