Uniswap V4 hooks

Uniswap V4 encodes hook permissions in the last 14 bits of the hook address. A hook can only register for a callback if the corresponding bit is set when the contract is deployed (typically via CREATE2 mining).

The scanner reads these bits directly from the address:

Bit	Permission
0x2000	beforeInitialize
0x1000	afterInitialize
0x0800	beforeAddLiquidity
0x0400	afterAddLiquidity
0x0200	beforeRemoveLiquidity
0x0100	afterRemoveLiquidity
0x0080	beforeSwap
0x0040	afterSwap
0x0020	beforeDonate
0x0010	afterDonate
0x0008	beforeSwapReturnDelta
0x0004	afterSwapReturnDelta
0x0002	afterAddLiquidityReturnDelta
0x0001	afterRemoveLiquidityReturnDelta

The four ReturnDelta permissions are particularly powerful — they let the hook mutate the swap's deltas, effectively setting custom fees or redirecting flow. The scanner escalates severity to high when any ReturnDelta bit is set.