Beanstalk Part 2

Summary

The Silo stores the raw amount of LP deposited as a reference for user deposit. This brings a major issue in the protocol's plan to shift from a WETH:Bean to a WSETH:Bean pool. This migration will break how liquidity values are tracked, causing errors in the representation of these values and creating potential differences in the amounts that users can withdraw.

Vulnerability Details

The main problem comes from switching the token pairs from WETH:Bean to WSETH:Bean. The migration moves all liquidity to the new pool. Once the migration is done users will have more LP amount in than before because after the migration is done the total LP value from the WSETH:Bean will be less than the one on the ETH:Bean pool.

Impact

Since WSETH typically has a different market value due to staking benefits, the LP tokens in the new pool will inherently have different values. This means users will end up withdrawing more than what they originally deposited.

Tools Used

• Manual Review

Recommendations

1. Adjustment Mechanism Migration: Make sure to adjust the value of the new LP tokens(WSETH:Bean) with the amount of LP tokens deposited in the Silo based on the current market prices of WETH and WSETH at the time of migration. This will ensure the new LP tokens issued are equal in value to the old ones, adjusted for any changes in market value.