Vulnerability Details

In upgradable contracts, there should be a storage location for variables to get added freely without causing any storage collision. In Bridge.sol we can see that the contract inherits from a lot of contracts each of them has its own variables.

Bridge.sol#L30

If we checked StarklaneState for example we will find that it has its own variables.

State.sol#L13-L22

Since the idea of upgrading the contract is either adding features or fixing issues, there can be new variables added. So any addition of new variables in one of the child contracts that Bridge inherits from them, will result in storage collision and corruption of all the contract states.

Impact

Inability to add new features / fix issues to the contract, which will require adding variables to contracts That Bridge inherit from it.

Tools Used

Manual Review

Recommendations

Adding Storage Gap to All Contracts that the Bridge contract Directly inherits from them, this includes UUPSOwnableProxied, StarklaneState, StarklaneEscrow, StarklaneMessaging, and CollectionManager.