Submitted by unforgiven
https://github.com/code-423n4/2022-06-notional-coop/blob/6f8c325f604e2576e2fe257b6b57892ca181509a/notional-wrapped-fcash/contracts/wfCashERC4626.sol#L177-L184
https://github.com/code-423n4/2022-06-notional-coop/blob/6f8c325f604e2576e2fe257b6b57892ca181509a/notional-wrapped-fcash/contracts/wfCashERC4626.sol#L168-L175
https://github.com/code-423n4/2022-06-notional-coop/blob/6f8c325f604e2576e2fe257b6b57892ca181509a/notional-wrapped-fcash/contracts/wfCashERC4626.sol#L225-L241
For some fcash the asset token is underlying token (asset.tokenType == TokenType.NonMintable) and NotionalV2 will not handle minting with useUnderlying==True for those fcashs (according to what I asked from sponsor). In summery most of the logics in wfCashERC4626 will not work for those fcash tokens.
when for some fcash asset token is underlying token, all calls to NotionalV2 should be with useUnderlying==False. but deposit() and mint() in wfCashERC4626 contract call _mintInternal() with useUnderlying==True and it calls NotionalV2.batchLend() with depositUnderlying==true so the NotionV2 call will fail for fcash tokens that asset token is underlying token and it would cause  that deposit() and mint()  logic wfCashERC4626  will not work and contract will be useless for those tokens.
_redeemInternal() issue is similar and it calls _burn() with redeemToUnderlying: true which execution eventually calls NotionalV2.batchBalanceAndTradeAction() with toUnderlying=True which will revert so _redeemInternal() will fail and because withdraw() and redeem use it, so they will not work too for those fcash tokens that asset token is underlying token.
This is deposit() and mint()  code in wfCashERC4626:
As you can see they both call _mintInternal() with last parameter as true which is useUnderlyings value. This is _mintInternal() code:
As you can see it calls NotionalV2 functions with useUnderlying=True but according to sponsor clarification NotionalV2 would fail and revert for those calls because useUnderlying=True and fcashs asset token is underlying token (asset.tokenType == TokenType.NonMintable).
So in summery for fcash tokens which asset token is underlying token NotionalV2 wont handle calls which include useUnderlying==True but in wfCashERC4626 contract functions like deposit(), mint(), withdraw() and redeem() they all uses useUnderlying==True always so wfCashERC4626 wont work for those specific type of tokens which asset token is underlying token(asset.tokenType == TokenType.NonMintable)
the detail explanations for functions withdraw() and redeem() are similar.
VIM
Check that if for that fcash token asset token  is underlying token or not and set useUnderlying based on that.
jeffywu (Notional) confirmed
gzeoneth (judge) decreased severity to Medium and commented:
