Submitted by aphak5010, also found by datapunk, arcoun, wait, unforgiven, and yixxas
The GiantPoolBase.withdrawLPTokens function (https://github.com/code-423n4/2022-11-stakehouse/blob/4b6828e9c807f2f7c569e6d721ca1289f7cf7112/contracts/liquid-staking/GiantPoolBase.sol#L69) allows to withdraw LP tokens from a GiantPool by burning an equal amount of GiantLP.
This allows a user to handle the LP tokens directly without the need for a GiantPool as intermediary.
It is not checked however whether the LP tokens to be withdrawn were transferred to the GiantPool in exchange for staking ETH.
I.e. whether the LP token are of any value.
There are two issues associated with this behavior.
The same issue exists for the GiantSavETHVaultPool.withdrawDETH function.
But in this case, the victim must also provide a wrong savETHVault address which makes this issue less likely to be exploited.
VSCode
The GiantPool should store information about which LP tokens it receives for staking ETH.
When calling the GiantPoolBase.withdrawLPTokens function it can then be checked if the LP tokens to be withdrawn were indeed transferred to the GiantPool in exchange for staking ETH.
vince0656 (Stakehouse) confirmed
