Core Contracts
Regnum Aurum Acquisition Corp
HardhatReal World AssetsNFT
77,280 USDC
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Submission Details
Severity: low
Invalid

Approval Race Condition

bareli

Summary

In liquidateBorrower, you use crvUSDToken.approve(address(lendingPool), scaledUserDebt).

This can lead to race conditions where a malicious contract can front-run and change the allowance before finalizeLiquidation is executed.

Vulnerability Details

function liquidateBorrower(address userAddress) external onlyManagerOrOwner nonReentrant whenNotPaused {
_update();
// Get the user's debt from the LendingPool.
uint256 userDebt = lendingPool.getUserDebt(userAddress);
uint256 scaledUserDebt = WadRayMath.rayMul(userDebt, lendingPool.getNormalizedDebt());
​
if (userDebt == 0) revert InvalidAmount();
​
uint256 crvUSDBalance = crvUSDToken.balanceOf(address(this));
if (crvUSDBalance < scaledUserDebt) revert InsufficientBalance();
​
// Approve the LendingPool to transfer the debt amount
bool approveSuccess = crvUSDToken.approve(address(lendingPool), scaledUserDebt);
if (!approveSuccess) revert ApprovalFailed();
// Update lending pool state before liquidation
lendingPool.updateState();
​
// Call finalizeLiquidation on LendingPool
lendingPool.finalizeLiquidation(userAddress);
​
emit BorrowerLiquidated(userAddress, scaledUserDebt);
}

}

Impact

Tools Used

Recommendations

Instead of approve, use safeIncreaseAllowance and safeDecreaseAllowance from SafeERC20.

  • Alternatively, use permit if crvUSDToken supports EIP-2612.

  • Another safer pattern is to call transfer directly rather than approving beforehand.

crvUSDToken.safeIncreaseAllowance(address(lendingPool), scaledUserDebt);

lendingPool.finalizeLiquidation(userAddress);

crvUSDToken.safeDecreaseAllowance(address(lendingPool), scaledUserDebt);

Updates

Lead Judging Commences

inallhonesty Lead Judge 7 months ago
Submission Judgement Published
Invalidated
Reason: Non-acceptable severity

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