Race Conditions and Business Logic Flaws in Node.js: Atomic Endpoints and TOCTOU Defenses [2026]
Your auth can be bulletproof while attackers drain your balance two requests at a time. Business logic flaws and race conditions are how 'correct' code loses money and data. Here's how check-then-act bugs actually happen in Node.js, and the atomic fixes — conditional updates, row-locked transactions, unique constraints, and idempotency keys — that close them.