Submitted by unforgiven
https://github.com/code-423n4/2022-12-tigris/blob/588c84b7bb354d20cbca6034544c4faa46e6a80e/contracts/BondNFT.sol#L206-L228 
https://github.com/code-423n4/2022-12-tigris/blob/588c84b7bb354d20cbca6034544c4faa46e6a80e/contracts/BondNFT.sol#L48-L86
Function BondNFT.createLock() creates a bond and it sets bonds mint epoch as epoch[asset]. Function Lock.lock() first calls claimGovFees() which calls BondNFT.distribute() for all assets and updates the epoch[assets] for all assets. So during normal bond creation, the value of epoch[asset] would be updated and bond would be created from today epoch to today+period epoch. But if totalShares[tigAsset] == 0 for an asset, then distribute() wont update epoch[asset] for that asset and epoch[asset] will be some old epoch(will be the start time where asset is added or the time where totalShares[_tigAsset] != 0). This would make createLock() set very wrong values for bonds mint epoch when totalShares[tigAsset] == 0.
This would happen for the first bond that has been created for that asset always and it will happen again if for some period totalShares[asset] become 0, then the next bond would have wrong mint epoch. or setAllowedAsset(asset, false)  has been called for that asset.
This is distribute() code in BondNFT contract:
As you can see when totalShares[_tigAsset] == 0, then the value of epoch[_tigAsset] wont get updated to today. And there is no other logic in the code to update epoch[tigAsset]. So when totalShares[_tigAsset] == 0, then the value of the epoch[tigAsset] would be outdated. this would happen when an asset is recently added to the BondNFT assets or when there is no bond left.
When this condition happens and a user calls Lock.lock() to create a bond, the lock() function would call claimGovFees() to update rewards in BondNFT but because for that asset the value of totalShares are 0, that asset epoch[] wont get updated and in the BondNFT.createLock(), the wrong value would set as bonds mint epoch.
This is Lock.lock() code:
And this is BondNFT.createLock() code:
If a bond gets wrong value for mint epoch, it would have wrong value for expired epoch and user would get a lot of shares by lock for small time. 
For example this scenario:
So attacker was able to create lock for a long time and get shares and rewards based on that, but attacker can release lock after short time.
VIM
Update epoch[asset] in distribute() function  even when totalShares[_tigAsset] is equal to 0. Only the division by zero and fund transfer should be prevented when totalShare is zero and epoch[asset] index should be updated.
TriHaz (Tigris Trade) confirmed 
Alex the Entreprenerd (judge) commented:
GainsGoblin (Tigris Trade) resolved:
