Submitted by cccz, also found by fatherOfBlocks,  Ruhum, csanuragjain, gzeon, IllIllI, GimelSec, dipp, berndartmueller, pedroais, horsefacts, AlleyCat, Bahurum, and shenwilly
In swapWithETH/buyAllAmountWithETH/offerWithETH/depositWithETH functions of the RubiconRouter contract, when msg.value > max_fill_withFee/pay_amt/amount/amtWithFee, the excess ether will not be returned to the user.
https://github.com/code-423n4/2022-05-rubicon/blob/8c312a63a91193c6a192a9aab44ff980fbfd7741/contracts/RubiconRouter.sol#L325-L339
https://github.com/code-423n4/2022-05-rubicon/blob/8c312a63a91193c6a192a9aab44ff980fbfd7741/contracts/RubiconRouter.sol#L383-L393
https://github.com/code-423n4/2022-05-rubicon/blob/8c312a63a91193c6a192a9aab44ff980fbfd7741/contracts/RubiconRouter.sol#L455-L462
https://github.com/code-423n4/2022-05-rubicon/blob/8c312a63a91193c6a192a9aab44ff980fbfd7741/contracts/RubiconRouter.sol#L494-L507
Return excess ether to msg.sender, or require msg.value == maxfillwithFee/pay_amt/amount/amtWithFee.
bghughes (Rubicon) confirmed
KenzoAgada (warden) commented:
