#41907 [SC-High] Unused debt is not send to Reward Claimer
Submitted on Mar 19th 2025 at 10:03:41 UTC by @Oxgritty for Audit Comp | Yeet
Report ID: #41907
Report Type: Smart Contract
Report severity: High
Target: https://github.com/immunefi-team/audit-comp-yeet/blob/main/src/StakeV2.sol
Impacts:
Contract fails to deliver promised returns, but doesn't lose value
Description
Brief/Intro
When a user calls claimRewards(claimRewardsInNative/ claimRewardsInToken0/ claimRewardsInToken1/ claimRewardsInToken) function, his reward is converted into his choice of token, during this swapping the amount of token which was not used will be send to StakeV2.sol instead of the user.
Vulnerability Details
When a user calls one of these functions(claimRewardsInNative/ claimRewardsInToken0/ claimRewardsInToken1/ claimRewardsInToken) to claim rewards and inside these functions we call a relevant zapOut function(like
Zapper::zapOutNative
forStakeV2::claimRewardsInNative
orZapper::zapOutToToken0
forStakingV2::claimRewardsInToken0
) in Zapper.sol, Zapper.sol pays back the amount of unused debt to StakeV2.sol and StakeV2 does not send it back to the user.
Impact Details
Reward Claimer loses unused debt, as it is transferred to StakeV2.sol
References
This issue is present in all 4 claimRewards function:
claimRewardsInNative After calling
Zapper::zapInNative
, we should send unused debt back to the user, but we are not doing it.
Same problem with these other 3 functions as well
claimRewardsInToken0
claimRewardsInToken1
claimRewardsInToken
Proof of Concept
Proof of Concept
Step 0: Assumptions we are making
Bob has rewards of 50e18 vaultShares that he wants to claim in Native Token(BERA) using
StakeV2::claimRewardsInNative
zapOutNative
will turn 50e18 worth of vaultShares into the following Balances45e18 (BERA)
2e18 (Token0)
3e18 (Token1)
Step 1: Calling StakeV2::claimRewardsInNative
StakeV2::claimRewardsInNative
Bob calls
StakeV2::claimRewardsInNative
withamountToWithdraw=50e18
and function is successfully executed.
Step 2: Checking Balances:
For StakeV2
Token0.balanceOf(address(StakeV2)) = 2e18
Token1.balanceOf(address(StakeV2)) = 3e18
BERA.balanceOf(address(StakeV2)) = 0
For Bob
Token0.balanceOf(address(Bob)) = 0
Token1.balanceOf(address(Bob)) = 0
BERA.balanceOf(address(Bob)) = 45e18
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