Beanstalk: The Finale

Summary

Missing checks for whether Arbitrum Sequencer is active

Vulnerability Detail

Considering Arbitrum is an L2 of consideration for BEANSTALK, its important to check for the sequencer's active status.

Chainlink recommends that users using price oracles, check whether the Arbitrum sequencer is active

https://docs.chain.link/data-feeds#l2-sequencer-uptime-feeds

If the sequencer goes down, the index oracles may have stale prices, since L2-submitted transactions (i.e. by the aggregating oracles) will not be processed.

Impact

Stale prices, e.g. if one of the tokens were to de-peg while the sequencer is offline, stale price is used and can result in innacurate price feeds.

Tool used

Manual Review

Recommendation

Use sequencer oracle to determine whether the sequencer is offline or not.