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Task: Crowdfunding service for purchasing items, router costs 333 with user balance always 0. Solution: JWT token reuse after rename creates ghost participants, integer division truncation (int(333/334)=0) allows free purchase.

$ ls tags/ techniques/
toctoufastapiauthentication_bypasspythonjwt_token_reusebusiness_logicinteger_divisionfile_based_storagecrowdfunding
JWT token reuse after renameInteger division truncation (int(333/334) = 0)TOCTOU in user existence checkGhost participant creation
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