Summary

DSCEngine.mintDsc allows to mint any small value. In case of liquidation, small debts can't be not interesting to liquidators, because gas cost will be bigger than potential gains from liquidation.

Vulnerability Details

DSCEngine.mintDsc function allows to mint stablecoin. The only check that it does is if amount to mint is bigger than 0.
Transaction on main net are not cheap. So in order to make liquidation attractive to the liquidator, gas fees should be less than gains from liquidation. Currently liquidator receives 10% of liquidated debt.

So in case if a lot of people will make 10$ mints(they then provide 20$ collateral) and these positions will go down, then it's likely possible that tx costs will be higher than 1$ gain. As result liquidators will ignore such accounts which will create bad debt and stable coin will not be backed fully anymore.

Impact

Stable coin will die.

Tools Used

VsCode

Recommendations

Do not allow to int less than some amount. Also do not allow to repay and leave less debt than that amount.