Reentrancy in `USDO.flashLoan()`, enabling an attacker to borrow unlimited USDO exceeding the max borrow limit

Collateral can be locked in BigBang contract when `debtStartPoint` is nonzero

Ability to steal user funds and increase collateral share infinitely in BigBang and Singularity

`totalCollateralShare` state variable not updated in `Singularity` market upon liquidation, resulting in an error on `addCollateral` with skim functionality

Understatement of `poolTotalPeUSDCirculation` amounts due to incorrect accounting after function `_repay` is called

Attacker may DOS auctions using invalid bid parameters

address.call{value:x}() should be used instead of payable.transfer()

Borrower/Lender excessive ETH not refunded and permanently locked in protocol

`_payoutToken[s]()` is not compatible with tokens with missing return value

transfer() depends on gas consts

The `unwrapETH2LD` use `transferFrom` instead of `safeTransferFrom` to transfer ERC721 token