😭Reliance On Fetching Oracle Functionality

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Unable to transfer WrappedIbbtc if Oracle goes down

Impact

Within the WrappedIbbtc contract, users will encounter an inability to execute transfers if oracle.pricePerShare() (found on Line 124) reverts. This issue arises because balanceToShares()—a function integral to both transfer and transferFrom methods—incorporates a call to pricePerShare(). This dependency means that any failure in pricePerShare() would incapacitate the transfer and transferFrom functionalities.

It's crucial to highlight that there is an inconsistency in behavior with WrappedIbbtcEth, which does not directly rely on oracle.pricePerShare() for transfers. Instead, WrappedIbbtcEth utilizes a cached value stored in a local variable pricePerShare. This cached value isn't continuously updated but rather refreshed only through calls to the updatePricePerShare() function.

Recommended Mitigation Steps

To rectify this inconsistency and potential transfer issue, careful review and modification of the contracts are necessary. Depending on the intended behavior specified in your design, you will need to adjust one of the contracts:

• If the design requires real-time price per share for transfers, consider updating WrappedIbbtcEth to mirror the behavior of WrappedIbbtc.

• Conversely, if the design allows for the use of cached values, you should adjust WrappedIbbtc to use a locally stored variable for pricePerShare similar to the approach in WrappedIbbtcEth.

Through these changes, you can ensure consistent and expected behaviors across the contracts, enhancing the reliability and functionality of the transfer processes in both contracts.

Should a Chainlink aggregator become stuck in a stale state then TwapOracle will become irrecoverably broken

Impact

Inability to call consult on the TwapOracle and so calculate the exchange rate between USDV and VADER.

Proof of Concept

Should any of the Chainlink aggregators used by the TwapOracle becomes stuck in such a state that the check on L143-146 of TwapOracle.sol consistently fails (through a botched upgrade, etc.) then the consult function will always revert.

https://github.com/code-423n4/2021-11-vader/blob/3a43059e33d549f03b021d6b417b7eeba66cf62e/contracts/twap/TwapOracle.sol#L143-L146

There is no method to update the address of the aggregator to use so the TwapOracle will be irrecoverable.

Recommended Mitigation Steps

Allow governance to update the aggregator for a pair (ideally with a timelock.)