Summary

Stepwise jump in pool rate can affect previously staked user' reward

Vulnerability Details

When users are claiming their staking reward with claim() in Distribution.sol, it will calculate the reward with the current pool rate

editPool() can change the pool rate, if the pool rate is changed, there will be a stepwise jump, the previous unclaimed staking reward will be calculated with the new rate

Impact

Users' staking reward will be affected

Tools Used

Manual review

Recommendations

Calculate reward before the rate change with the old rate and the reward after the rate change with the new rate