#58076 [SC-Insight] Fix unit mismatch in _doLiquidation: collateralInUnderlying -> collateralInDebt

Submitted on Oct 30th 2025 at 13:05:06 UTC by @wylis for Audit Comp | Alchemix V3

Report ID: #58076
Report Type: Smart Contract
Report severity: Insight
Target: https://github.com/alchemix-finance/v3-poc/blob/immunefi\\_audit/src/AlchemistV3.sol
Impacts:

Description

Brief

The liquidation path mixes up parameter naming/units in AlchemistV3._doLiquidation(). The argument named collateralInUnderlying is actually expected to be expressed in debt tokens. While current call sites may be correct, the inconsistency creates a high risk of future regressions where a developer passes an underlying-denominated value, leading to mispriced liquidations and incorrect fee calculations.

Details

Current code reads:


    /// @param collateralInUnderlying The total collateral value of the account in debt tokens.

The parameter name is wrong, but the NatSpec is right.

The name collateralInUnderlying indicates “in underlying tokens,” but the doc string says “in debt tokens.” The function downstream (calculateLiquidation) expects a debt-denominated value, so the parameter name is misleading.

Impact

This is submitted as an Insight (documentation/naming inconsistency). However, if a future change misuses the parameter due to the name, realistic downstream impacts include: under- or over-liquidation, incorrect fee routing, or invariant breaks under market moves.

Recommendation

-    /// @param collateralInUnderlying The total collateral value of the account in debt tokens.
+    /// @param collateralInDebt The total collateral value of the account in debt tokens.
     /// @param repaidAmountInYield The amount of debt repaid in yield tokens.
-    function _doLiquidation(uint256 accountId, uint256 collateralInUnderlying, uint256 repaidAmountInYield)
+    function _doLiquidation(uint256 accountId, uint256 collateralInDebt, uint256 repaidAmountInYield)
         internal
         returns (uint256 amountLiquidated, uint256 feeInYield, uint256 feeInUnderlying)
     {
         Account storage account = _accounts[accountId];

         (uint256 liquidationAmount, uint256 debtToBurn, uint256 baseFee, uint256 outsourcedFee) = calculateLiquidation(
-            collateralInUnderlying,
+            collateralInDebt,
             ...
         );

Proof of Concept

N/A for doc report.