Submitted by reassor
https://github.com/code-423n4/2022-06-nibbl/blob/8c3dbd6adf350f35c58b31723d42117765644110/contracts/Utilities/NibblVaultFactoryData.sol#L6
https://github.com/code-423n4/2022-06-nibbl/blob/8c3dbd6adf350f35c58b31723d42117765644110/contracts/NibblVaultFactory.sol#L158-L169
https://github.com/code-423n4/2022-06-nibbl/blob/8c3dbd6adf350f35c58b31723d42117765644110/contracts/NibblVault.sol#L37
User can buy out NFT by initiating the process through initiateBuyout, then he has to wait BUYOUT_DURATION which is 5 days and if the buyout will not get rejected he can claim the NFT. During that period bidder cannot cancel the process. The issue is that since NibblVault is used through proxy it is possible to change its implementation through administrative functionality in NibblVaultFactory and the timelock for updateing implementation is only 2 days.
Attack Scenario:
Manual Review / VSCode
It is recommended to either implement functionality for bidder to cancel the bid or increase/decrease the UPDATE_TIME/BUYOUT_DURATION so the invariant BUYOUT_DURATION < UPDATE_TIME holds.
mundhrakeshav (Nibbl) acknowledged, but disagreed with severity 
HardlyDifficult (judge) decreased severity to Medium and commented:
