Fractal Protocol's USDF vault on Arbitrum was drained of 13,700 USDC.e via re-entrant flashloan attack. The attacker looped through Balancer V2 batchSwap callbacks to recursively call the vault's deposit and withdraw functions. The vault's tokenPrice accrued only once daily and its share arithmetic rounded favorably for the depositor, allowing each re-entrant round-trip to extract more than it put in.