Alchemix Transmuter

Summary

Vulnerability Details

As off my understanding whole Use case of this codebase is

The keeper's actions exploit the price discrepancy between alETH and WETH:

• Claiming WETH at the peg value (1:1 ratio).

• Buying back alETH at a discount during the depeg event.

• The profit comes from the premium (difference in alETH price), which is effectively arbitraged.

So may be in sometime (depeg time) both alETH and WETH will not be 1:1, one will be smaller than other

But in below function its adding both type of assets and return result as they both always be 1:1 , So in Depeg situation like above function will return wrong output amount.

https://github.com/Cyfrin/2024-12-alchemix/blob/main/src/StrategyArb.sol#L122-L124

Impact

Tools Used

Manual review

Recommendations

Possible solution is that function only return in One typr asset

I mean it will return output in Either in WETHform or in alETHform

alETH will be suit us more and justify function name

• so first function should add both UnexchangedBalance and alETH balnce of this contract

• then fetch claimable balance(weth from Transmuter) and add with any weth present in that contract

• then called any Dex to fetch current price of weth in term of alETH (Its not swap just a view call to know current price action)

• then finally add this with previous sumed alETH balnce and return that.