AutoleverageBase: Must approve 0 first

Lines of code Vulnerability details Impact Some tokens like USDT do not work when changing the allowance from an existing non-zero allowance value.They must first be approved by zero and then the actual allowance must be approved. Proof of Concept Tools Used None Recommended Mitigation Steps...

YearnTokenAdapter's wrap can become stuck as it uses one step approval for an arbitrary underlying

Lines of code Vulnerability details Some tokens do not allow for approval of positive amount when allowance is positive already to handle approval race condition, most known example is USDT. This can cause the function to stuck whenever a combination of such a token and leftover approval be met...

ERC20 transfers does not work on non-standard compliant tokens like USDT

Lines of code Vulnerability details Impact PermissionlessBasicPoolFactory.sol Consider this function: function deposituint poolId, uint amount external Pool storage pool = poolspoolId; requirepool.id == poolId, 'Uninitialized pool'; requireblock.timestamp pool.startTime, 'Cannot deposit before po...

Transfers Will Revert On Non-Standard ERC20 Token Contracts

Lines of code Vulnerability details Impact There are several contracts which do not utilise OpenZeppelin's SafeERC20 library when performing token transfers. The FactoryDAO suite of smart contracts intends to support transfers by all tokens, including non-standard tokens such as USDT which does n...

The Contract Should approve(0) first

Originally submitted by warden defsec in 198, duplicate of 178 related to the use of safeApprove. This is upgraded from a QA report to standalone issue because it correctly described the revert when trying to call safeApprove on non-zero allowance. QA report that only describe safeApprove as...

SuperVault's leverageSwap and emptyVaultOperation can become stuck

Lines of code Vulnerability details leverageSwap and emptyVaultOperation can be run repeatedly for the same tokens. If these tokens happen to be an ERC20 that do not allow for approval of positive amount when allowance already positive, both functions can become stuck. In both cases logic doesn't...

Missing support for ERC20 with fee

Lines of code Vulnerability details Impact Contract AaveV3YieldSource allows depositing tokens via supplyTokenTo function. Amount of tokens to transfer is based on passed argument depositAmount and is missing support for tokens with built-in fees. One of the popular tokens that implements such a...

Yield source cannot deposit fee-on-transfer tokens

Lines of code Vulnerability details Some ERC20 tokens, such as USDT, allow for charging a fee any time transfer or transferFrom is called. If a contract does not allow for amounts to change after transfers, subsequent transfer operations based on the original amount will revert due to the contrac...

Must approve 0 first

Lines of code Vulnerability details Impact Some tokens like USDT do not work when changing the allowance from an existing non-zero allowance value.They must first be approved by zero and then the actual allowance must be approved. Proof of Concept Tools Used None Recommended Mitigation Steps Use...

Not calling approve(0) before setting a new approval causes the call to revert when used with Tether (USDT)

Lines of code Vulnerability details Some tokens do not implement the ERC20 standard properly but are still accepted by most code that accepts ERC20 tokens. For example Tether USDT's approve function will revert if the current approval is not zero, to protect against front-running changes of...

Multiple missing approve(spender, 0) before approve(spender, amount)

Lines of code Vulnerability details Impact There are a few instances of missing calls to the IERC20 interface's approve function. The allowance needs to be set to 0 by calling for a given address and spender IERC20address.approvespender, 0. Not only do tokens like USDT require the allowance to be...

Pool Credit Line May Not Able to Start When _borrowAsset is Non ERC20 Compliant Tokens

Lines of code Vulnerability details Impact IERC20borrowAsset.transferto, fee; If the USDT token is supported as borrowAsset, the unsafe version of .transferto, fee may revert as there is no return value in the USDT token contract’s transfer implementation but the IERC20 interface expects a return...

Calling approve() without first calling approve(0) causes problems with non-standard tokens (e.g. USDT)

Lines of code Vulnerability details This is another instance of the same issue that was found in the last sublime contest. In that issue the judge upgraded the finding to a risk of Medium. Impact Calling approve without first calling approve0 will revert with some tokens, such as Tether USDT. Thi...

approve and safeApprove Should Approve the Zero Amount First

Lines of code Vulnerability details Impact The PooledCreditLine.sol and LenderPool.sol contracts approve the strategy contract on the collateral or borrow assets before depositing funds. This allows the strategy contracts to transfer on behalf of these contracts, pulling assets out from the pool...

Must approve 0 first

Lines of code Vulnerability details Impact Some tokens like USDT do not work when changing the allowance from an existing non-zero allowance value.They must first be approved by zero and then the actual allowance must be approved. Proof of Concept Tools Used None Recommended Mitigation Steps Use...

Use of IERC20.transfer() instead of SafeERC20.safeTransfer()

Lines of code Vulnerability details Impact There are multiple external calls to IERC20.transfer that suppose to transfer out tokens from the system. However, there are tokens like USDT that don't return any return value in their implementation of the transfer function, so calling IERC20.transfer ...

non erc20 token might revert when calling emergencyWithdrawERC20()

Lines of code Vulnerability details Impact when there is an emergency situation, the admin can call emergencyWithdrawERC20 to save the funds, however due to mismatch between non erc20 token like USDT and openzeppelin IERC20 where the open zeppelin IERC20 is expecting a return on the transfer...

Cvx3CrvOracle does not check that Chainlink data is fresh.

Handle TomFrenchBlockchain Vulnerability details Impact Usage of stale prices when querying chainlink oracles. Proof of Concept Cvx3CrvOracle queries chainlink oracles for the prices of DAI, USDC and USDT, however it doesn't require that the response is fresh by checking which round the answer wa...

transfer return value of a general ERC20 is ignored

Handle mics Vulnerability details Need to use safeTransfer instead of transfer. As there are popular tokens, such as USDT that transfer/trasnferFrom method doesn’t return anything. The transfer return value has to be checked as there are some other tokens that returns false instead revert, that...

transfer return value of a general ERC20 is ignored

Handle pants Vulnerability details Need to use safeTransfer instead of transfer. As there are popular tokens, such as USDT that transfer/trasnferFrom method doesn’t return anything. The transfer return value has to be checked as there are some other tokens that returns false instead revert, that...