DEX aggregator 0x said its review of 84,163 Uniswap v4 Hooks across six chains found that 54.2% were malicious and 26.4% were likely malicious as of Sept. 11. The firm said certain Hooks advertise favorable prices to win an aggregator's route, then impose fees or worse pricing at settlement, leaving users with as much as 50% less than quoted. 0x identified live examples on Base and BNB Chain that charged substantial fees on selected trades. The findings prompted a dispute over responsibility in permissionless liquidity pools. 0x said Hook design creates adverse incentives and that trade simulation can fail when Hooks recognize simulated transactions. Uniswap founder Hayden Adams, Uniswap's Niko Kampouris and Paradigm's Dan Robinson said aggregators should vet the Hooks they route through, pointing to Uniswap's allowlist and API. 0x engineer Duncan Townsend said 0x already uses the list but found a malicious Hook on it and said useful Hooks can await inclusion. Uniswap v4 held $1.06 billion in total value locked on Sept. 15 after rising 39.9% over 30 days, according to DefiLlama. The protocol processed $38.12 billion in DEX volume during that period, while UNI traded at $6.35, CoinGecko data showed.