Lines of code

https://github.com/code-423n4/2024-05-munchables/blob/57dff486c3cd905f21b330c2157fe23da2a4807d/src/managers/LockManager.sol#L177-L207

Vulnerability details

The approveUSDPrice() function allows price feed role holders to approve prices after disapproving as there is no check for it the caller has already voted to disapprove the role

    function approveUSDPrice(
        uint256 _price
    )
        external
        onlyOneOfRoles(
            [
                Role.PriceFeed_1,
                Role.PriceFeed_2,
                Role.PriceFeed_3,
                Role.PriceFeed_4,
                Role.PriceFeed_5
            ]
        )
    {
        if (usdUpdateProposal.proposer == address(0)) revert NoProposalError();
        if (usdUpdateProposal.proposer == msg.sender)
            revert ProposerCannotApproveError();
        if (usdUpdateProposal.approvals[msg.sender] == _usdProposalId)
            revert ProposalAlreadyApprovedError();
        if (usdUpdateProposal.proposedPrice != _price)
            revert ProposalPriceNotMatchedError();

        usdUpdateProposal.approvals[msg.sender] = _usdProposalId;
        usdUpdateProposal.approvalsCount++;

        if (usdUpdateProposal.approvalsCount >= APPROVE_THRESHOLD) {
            _execUSDPriceUpdate();
        }

        emit ApprovedUSDPrice(msg.sender);
    }

This breaks the whole system of voting as voters are required to pick a side and not support both sides

Impact

price feed role holders can vote to approve a price after rejecting or declining the proposed price thereby filling up both sides of the threshold and preventing other role holders from voting.

Tools Used

manual review

Recommended Mitigation Steps

The approveUSDPrice() function should be corrected to prevent role holder that have already disapproved the price from calling it

    function approveUSDPrice(
        uint256 _price
    )
        external
        onlyOneOfRoles(
            [
                Role.PriceFeed_1,
                Role.PriceFeed_2,
                Role.PriceFeed_3,
                Role.PriceFeed_4,
                Role.PriceFeed_5
            ]
        )
    {
        if (usdUpdateProposal.proposer == address(0)) revert NoProposalError();
        if (usdUpdateProposal.proposer == msg.sender)
            revert ProposerCannotApproveError();
++      if (usdUpdateProposal.disapprovals[msg.sender] == _usdProposalId)
++          revert ProposalAlreadyDisapprovedError();
        if (usdUpdateProposal.approvals[msg.sender] == _usdProposalId)
            revert ProposalAlreadyApprovedError();
        if (usdUpdateProposal.proposedPrice != _price)
            revert ProposalPriceNotMatchedError();

        usdUpdateProposal.approvals[msg.sender] = _usdProposalId;
        usdUpdateProposal.approvalsCount++;

        if (usdUpdateProposal.approvalsCount >= APPROVE_THRESHOLD) {
            _execUSDPriceUpdate();
        }

        emit ApprovedUSDPrice(msg.sender);
    }

Assessed type

Other

code-423n4 / 2024-05-munchables-findings