Funny Merlot Yeti - ownership_change state is not migrated to split NFTs in VotingEscrow

[sherlock-admin4]

Funny Merlot Yeti

Low/Info

ownership_change state is not migrated to split NFTs in VotingEscrow

Summary

The ownership_change state is set when a NFT is transferred. However, this state is not migrated when splitting it.

Vulnerability Detail

When an NFT is transferred, the _transferFrom function sets the block of ownership transfer as following: `ownership_change[_tokenId] = block.number; (link to code)

This value is only checked by the function balanceOfNFT:

function balanceOfNFT(uint _tokenId) external view returns (uint) {
    if (ownership_change[_tokenId] == block.number) return 0;
    return _balanceOfNFT(_tokenId, block.timestamp);
}

An user can bypass this check by calling the split function, where a new NFT with a value of up to _locked.amount -1 is created. The ownership_change mapping is not updated for the newly created NFT.

Impact

Low severity issue

Code Snippet

Tool used

Manual Review

Recommendation

Update the status of the newly created NFT, and thus removing the possibility to sidestep this lock