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

Incorrect Application of Liquidation Threshold Check in Borrowing Logic

modey

Summary

In LendingPool::Borrowthe logic incorrectly multiplies the liquidationThreshold by the debt instead of collateral Value.

Vulnerability Details

The current implementation incorrectly checks whether a borrower's collateral is sufficient by comparing collateralValue directly against userTotalDebt.percentMul(liquidationThreshold).

Inatead of applying multiplication of liquidationThreshold to the collateralValueit nby the collateralValue.

https://github.com/Cyfrin/2025-02-raac/blob/89ccb062e2b175374d40d824263a4c0b601bcb7f/contracts/core/pools/LendingPool/LendingPool.sol#L344

Impact

Users can borrow more than they should. The protocol is underestimating the amount of collateral required, allowing users to borrow more than they should be able to.

Tools Used

Manual Review

Recommendations

It can be fixed like this:

function borrow(uint256 amount) external nonReentrant whenNotPaused onlyValidAmount(amount) {
if (isUnderLiquidation[msg.sender]) revert CannotBorrowUnderLiquidation();
​
UserData storage user = userData[msg.sender];
​
uint256 collateralValue = getUserCollateralValue(msg.sender);
​
if (collateralValue == 0) revert NoCollateral();
​
// Update reserve state before borrowing
ReserveLibrary.updateReserveState(reserve, rateData);
​
// Ensure sufficient liquidity is available
_ensureLiquidity(amount);
​
// Fetch user's total debt after borrowing
uint256 userTotalDebt = user.scaledDebtBalance.rayMul(reserve.usageIndex) + amount;
​
// Ensure the user has enough collateral to cover the new debt
- if (collateralValue < userTotalDebt.percentMul(liquidationThreshold)) {
revert NotEnoughCollateralToBorrow();
}
​
+ if (collateralValue.percentMul(liquidationThreshold) < userTotalDebt) {
revert NotEnoughCollateralToBorrow();
}
​
// Update user's scaled debt balance
uint256 scaledAmount = amount.rayDiv(reserve.usageIndex);
​
​
// Mint DebtTokens to the user (scaled amount)
(bool isFirstMint, uint256 amountMinted, uint256 newTotalSupply) = IDebtToken(reserve.reserveDebtTokenAddress).mint(msg.sender, msg.sender, amount, reserve.usageIndex);
​
// Transfer borrowed amount to user
IRToken(reserve.reserveRTokenAddress).transferAsset(msg.sender, amount);
​
user.scaledDebtBalance += scaledAmount;
// reserve.totalUsage += amount;
reserve.totalUsage = newTotalSupply;
​
// Update liquidity and interest rates
ReserveLibrary.updateInterestRatesAndLiquidity(reserve, rateData, 0, amount);
​
// Rebalance liquidity after borrowing
_rebalanceLiquidity();
​
emit Borrow(msg.sender, amount);
}
Updates

Lead Judging Commences

inallhonesty Lead Judge 5 months ago
Submission Judgement Published
Validated
Assigned finding tags:

LendingPool::borrow as well as withdrawNFT() reverses collateralization check, comparing collateral < debt*0.8 instead of collateral*0.8 > debt, allowing 125% borrowing vs intended 80%

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