Summary

There is no input validation for "collateral" address in the external function liquidate().

Vulnerability Details

The liquidate() function in the DSCEngine.sol smart contract can be called with any address as the "collateral" address. However, doing so while creating the priceFeed object at line 344 will cause the transaction to be reverted.

[https://github.com/Cyfrin/2023-07-foundry-defi-stablecoin/blob/d1c5501aa79320ca0aeaa73f47f0dbc88c7b77e2/src/DSCEngine.sol#L344]

AggregatorV3Interface priceFeed = AggregatorV3Interface(s_priceFeeds[token]);

Impact

When the function "liquidate()" is invoked with a non-collateral address, the transaction will be reverted.

Tools Used

Manual Review

Recommendations

Adding "isAllowedToken(collateral)" modifer to "liquidate()" function