mVeNFT DOS - can't trigger the vote function

[c4-bot-2]

Lines of code

https://github.com/code-423n4/2024-09-fenix-finance/blob/main/contracts/core/VoterUpgradeableV2.sol#L485
https://github.com/code-423n4/2024-09-fenix-finance/blob/main/contracts/core/VoterUpgradeableV2.sol#L448

Vulnerability details

Description

The VoterUpgradeableV2.sol contract has the function attachToManagedNFT(), users use it to delegate their veFNX voting power to a mVeNFT.
One of the things this function does after receiving the new voting power is sub-call to _poke() and it will update the Last voted Timestamp of the mVeNFT

lastVotedTimestamps[tokenId_] = _epochTimestamp() + 1;

At this point, the mVeNFT can't trigger the vote function until the next epoch starts due to the _checkVoteDelay().
even this check inside the vote() doesn't help in this case

if (!managedNFTManagerCache.isWhitelistedNFT(tokenId_)) {
            _checkEndVoteWindow();
        }

However, to make things worse this protocol is deployed on Blast transactions are too cheap
malicious users can keep creating new locks every epoch with one wei in amount to bypass the zero check

File: VotingEscrowUpgradeableV2.sol#_createLock()

 LibVotingEscrowValidation.checkNoValueZero(amount_);

then at the start of every new epoch (after the start of the voting window) just call attachToManagedNFT()
By doing this it keeps forcing the mVeNFT to vote to the same gauges.

Impact

DOS attack.
mVeNFT can't invoke the vote function to change the weight of gauges.
mVeNFT can't reset its votes.

Tools Used

Manual Review

Recommended Mitigation Steps

One solution is to not check the vote delay, However, I believe this comes with some trade-off

    function vote(
        uint256 tokenId_,
        address[] calldata poolsVotes_,
        uint256[] calldata weights_
    ) external nonReentrant onlyNftApprovedOrOwner(tokenId_) {
        if (poolsVotes_.length != weights_.length) {
            revert ArrayLengthMismatch();
        }
        bool x = managedNFTManagerCache.isWhitelistedNFT(tokenId_);
        if (!x) {
        _checkVoteDelay(tokenId_);
        }

        _checkStartVoteWindow();
        IManagedNFTManager managedNFTManagerCache = IManagedNFTManager(managedNFTManager);
        if (managedNFTManagerCache.isDisabledNFT(tokenId_)) {
            revert DisabledManagedNft();
        }
        if (!x) {
            _checkEndVoteWindow();
        }
        _vote(tokenId_, poolsVotes_, weights_);
        _updateLastVotedTimestamp(tokenId_);
    }

Assessed type

DoS

[c4-judge]

alcueca marked the issue as duplicate of #9

[c4-judge]

alcueca marked the issue as satisfactory

[c4-judge]

alcueca changed the severity to 2 (Med Risk)

[c4-judge]

alcueca marked the issue as selected for report