Submitted by hyh, also found by 0x29A, 0xf15ers, 0xkowloon, 0xNineDec, berndartmueller, byterocket, cccz, codexploder, GreyArt, horsefacts, IllIllI, Kenshin, kenzo, KIntern, Lambda, obront, obtarian, oyc109, peritoflores, rajatbeladiya, rfa, saian, unforgiven, WatchPug, Wayne, and zer0dot_
ETH fees accumulated from takeOrders() and takeMultipleOneOrders() operations are permanently frozen within the contract as there is only one way designed to retrieve them, a rescueETH() function, and it will work as intended, not being able to access ETH balance of the contract.
Setting the severity as high as the case is a violation of systems core logic and a permanent freeze of ETH revenue of the project.
Fees are accrued in user-facing takeOrders() and takeMultipleOneOrders() via the following call sequences:
While token fees are transferred right away, ETH fees are kept with the InfinityExchange contract:
https://github.com/code-423n4/2022-06-infinity/blob/765376fa238bbccd8b1e2e12897c91098c7e5ac6/contracts/core/InfinityExchange.sol#L1119-L1141
i.e. when currency is ETH the fee part of the amount, protocolFee, is left with the InfinityExchange contract.
The only way to retrieve ETH from the contract is rescueETH() function:
https://github.com/code-423n4/2022-06-infinity/blob/765376fa238bbccd8b1e2e12897c91098c7e5ac6/contracts/core/InfinityExchange.sol#L1228-L1232
However, it cannot reach ETH on the contract balance as msg.value is used as the amount to be sent over. I.e. only ETH attached to the rescueETH() call is transferred from owner to destination. ETH funds that InfinityExchange contract holds remain inaccessible.
Consider adding contract balance to the funds transferred:
nneverlander (Infinity) confirmed 
HardlyDifficult (judge) commented:
