Submitted by gzeon, also found by Trust, Trust, and cccz
The only check on a new proposal is that it is priced lower than the existing proposal. It does not constrain on the _collateral supplied (except it will revert in \_verifyBalance if set to 0). Anyone can block normal proposal creation by creating a proposal with lower price but \_collateral == 1. When a high total supply is used, the price of each Rae is negligible and enables an attacker to DOS the protocol.
This violated the prevent a user from holding a vault hostage and never letting the piece be reasonably bought requirement.
For any proposal, an attacker can deny it with \_collateral = 1 and \_price = price - 1.
If he does not want the NFT to be sold, he can reject the proposal himself, resetting the contract state.
https://github.com/code-423n4/2022-12-tessera/blob/f37a11407da2af844bbfe868e1422e3665a5f8e4/src/seaport/modules/OptimisticListingSeaport.sol#L112-L116
Add this test to OptimisticListingSeaport.t.sol:
[FAIL. Reason: Call did not revert as expected]
Foundry
Require the total value of the new collateral to be greater than the previous.
This however still allows a Rae holder with sufficiently large holding to block proposal by creating a new proposal and immediately reject it himself.
stevennevins (Tessera) confirmed
HickupHH3 (judge) commented:
