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Race Condition
Hard
Race Condition
Double-redeem a gift card with parallel requests.
Mission briefing
GiftDrop runs a wallet system where promo codes credit balance once per account. Redemption is handled by a single slow database update. Find out whether firing many requests at once can apply the same code more than once.
0 / 1 tasks
0 / 20 pts
Room cleared
Every task in this room is done. Your rank progress just moved forward.
Objectives
- Get wallet ≥ 200 via race
Task 1 Double redeem Hard 20 pts
Scenario
GiftDrop credits one hundred dollars when you redeem code GIFT100. The wallet update reads balance, adds credit, then writes back without locking. Fire parallel redemptions so the same code pays out twice.
Your approach
- Reset the lab wallet if needed and note starting balance.
- Use the parallel redeem button or send many simultaneous POST requests.
- Refresh balance until it shows at least two hundred dollars.
- Copy the race success flag from the page.
- Submit the double-redeem flag.
Race GIFT100 redemptions.
Open lab →Hint
Use the parallel redeem button; reset if needed