First Flight #21: KittyFi
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Submission Details
Severity: high
Valid

Incorrect Collateral Value in Euros in KittyVault::getUserVaultMeowllateralInEuros

ayamercy

Summary

The function KittyVault::getUserVaultMeowllateralInEuros returns an incorrect value for the user's collateral in euros due to errors in the calculation involving price feeds and precision handling.

Vulnerability Details

The function getUserVaultMeowllateralInEuros is responsible for converting a user's collateral value from its native currency to euros. However, the calculation incorrectly handles the precision of the price feed data, leading to an inaccurate euro value for the user's collateral.

The problematic code is as follows:

function getUserVaultMeowllateralInEuros(address _user) external view returns (uint256) {
(, int256 collateralToUsdPrice, , , ) = i_priceFeed.latestRoundData();
(, int256 euroPriceFeedAns, , ,) = i_euroPriceFeed.latestRoundData();
@> uint256 collateralAns = getUserMeowllateral(_user).mulDiv(uint256(collateralToUsdPrice) * EXTRA_DECIMALS, PRECISION);
@> return collateralAns.mulDiv(uint256(euroPriceFeedAns) * EXTRA_DECIMALS, PRECISION);
}
PoC

Add the following to KittyFiTest.t.sol test file:

function test_userCollateralInEuros() public userDepositsCollateral {
uint256 userCollateral = wethVault.getUserVaultMeowllateralInEuros(user);
(, int256 usd,,,) = i_priceFeed.latestRoundData(); // ETH/USD
(, int256 eur,,,) = i_euroPriceFeed.latestRoundData(); // USD/EUR
uint256 usd_uint = uint256(usd);
uint256 eur_uint = uint256(eur);
​
​
uint256 realUserCollateral = ((wethVault.getUserMeowllateral(user) * usd_uint * 1e10 / 1e18) * eur_uint * 1e10 / 1e18)/1e18;
​
console.log("USD price feed:", usd);
console.log("EUR price feed:", eur);
console.log("userCollateral",userCollateral);
console.log("RealUserCollater:", realUserCollateral);
​
assert(userCollateral >= realUserCollateral * 1e18);
​
}

Impact

  • Incorrect Financial Calculations: The incorrect collateral value in euros could lead to erroneous financial decisions, affecting the accuracy of transactions, risk assessments, and liquidation processes.

  • Potential Under/Overestimation: Users may either be under-credited or over-credited for their collateral, leading to imbalances in the system and possible financial losses.

Tools Used

  • Manual review

  • Foundry (Testing Framework)

Recommendations

  • Correct Precision Handling: Adjust the calculation to properly handle the precision of price feed values, ensuring accurate conversion from the user's native collateral to euros

Updates

Lead Judging Commences

shikhar229169 Lead Judge about 1 year ago
Submission Judgement Published
Validated
Assigned finding tags:

`getUserVaultMeowllateralInEuros` doesn't considers the collateral decimals, instead uses constant precision which works only for 18 decimals

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