Submitted by rvierdiiev, also found by bin2chen
https://github.com/code-423n4/2023-01-popcorn/blob/main/src/vault/VaultController.sol#L605-L615
https://github.com/code-423n4/2023-01-popcorn/blob/main/src/vault/adapter/abstracts/AdapterBase.sol#L575
Anyone who uses same adapter has the ability to pause it. As result you have the ability to pause any vault by creating your vault with the same adapter.
When a user creates vault, he has the ability to deploy new adapter or reuse already created adapter.
VaultController gives ability to pause adapter. 
https://github.com/code-423n4/2023-01-popcorn/blob/main/src/vault/VaultController.sol#L605-L615
As you can see _verifyCreatorOrOwner is used to determine if msg.sender can pause adapter. 
https://github.com/code-423n4/2023-01-popcorn/blob/main/src/vault/VaultController.sol#L667-L670
So in case if you are creator of vault that uses adaptor that you want to pause, then you are able to pause it.
This is how it can be used in order to stop the vault.
So this attack allows to stop all vaults that use same adapter from earning yields.
VS Code
I think that its better to create a clone of adapter for the vault, so each vault has separate adapter.
RedVeil (Popcorn) acknowledged, but disagreed with severity 
