Safe transfers of tokens

Handle pauliax Vulnerability details Impact Not every ERC20 token returns true on transfer success. To support different tokens, the current best practice is to use SafeERC20 safeTransfer, safeTransferFrom, etc: Similarly, some ERC20 tokens like USDT require resetting the approval to 0 first befo...

uToken ERC20 approve method missing return value check #L109

Handle defsec Vulnerability details Impact The initiateVaultFillingZcTokenInitiate function performs an ERC20.approve call but does not check the success return value. Some tokens do not revert if the approval failed but return false instead. Proof of Concept 1. Navigate to "" 2...

Erc20.transferFrom() doesn't work on non-standard compliant tokens like USDT

Handle pants Vulnerability details Non-standard compliant tokens like USDT don't return a return value on transferFrom. The function Erc20.transferFrom reverts if the token doesn't return a return value, as it is defined to always return a boolean. Impact When using any non-standard compliant tok...

Erc20.approve() doesn't work on non-standard compliant tokens like USDT

Handle pants Vulnerability details Non-standard compliant tokens like USDT don't return a return value on approve. The function Erc20.approve reverts if the token doesn't return a return value, as it is defined to always return a boolean. Impact When using any non-standard compliant token like...

Erc20.transfer() doesn't work on non-standard compliant tokens like USDT

Handle pants Vulnerability details Non-standard compliant tokens like USDT don't return a return value on transfer. The function Erc20.transfer reverts if the token doesn't return a return value, as it is defined to always return a boolean. Impact When using any non-standard compliant token like...

Erc20.transferFrom() return value is ignored

Handle pants Vulnerability details According to the ERC-20 Token Standard, the function transferFrom returns false on failure. However, the return value of Erc20.transferFrom is ignored 11 times: 1. In Swivel.initiateVaultFillingZcTokenInitiate, line 103. 2. In...

ERC20 return values not checked

Handle cmichel Vulnerability details The ERC20.approve function returns a boolean value indicating success. This parameter needs to be checked for success. The Basket.approveUnderlying function does not check the return value of the IERC20tokensi.approve call. Neither does it work with tokens tha...

No ERC20 safe* versions called

Handle cmichel Vulnerability details Some tokens like USDT don't correctly implement the EIP20 standard and their transfer/transferFrom function return void instead of a success boolean. Calling these functions with the correct EIP20 function signatures will always revert. The...

Unhandled return value of transfer() could cause bounty payment failure

Handle 0xRajeev Vulnerability details Impact ERC20 implementations are not always consistent. Some implementations of transfer and transferFrom could return ‘false’ on failure instead of reverting. It is safer to wrap such calls into require statements or use safe wrapper functions implementing...

ERC20 return values not checked

Handle cmichel Vulnerability details The ERC20.transfer and ERC20.transferFrom functions return a boolean value indicating success. This parameter needs to be checked for success. Some tokens do not revert if the transfer failed but return false instead. The Manager.recoverToken function does not...

VaultHelper deposits don't work with fee-on transfer tokens

Handle cmichel Vulnerability details There are ERC20 tokens that may make certain customizations to their ERC20 contracts. One type of these tokens is deflationary tokens that charge a certain fee for every transfer or transferFrom. Others are rebasing tokens that increase in value over time like...

Possibility to Stake Twice

Handle verifyfirst Vulnerability details Impact Potential for some users to double-stake their Yaxis. Proof of Concept // SPDX-License-Identifier: MIT pragma solidity 0.6.12; import "@openzeppelin/contracts/token/ERC20/ERC20.sol"; import "@openzeppelin/contracts/token/ERC20/SafeERC20.sol"; // yAx...

nTokenAction does not emit Approval events

Handle cmichel Vulnerability details Vulnerability Details The nTokenAction is supposed to mimic the ERC20 but the allowance changes do not emit the Approval event in nTokenTransferFrom. Impact Off-chain scripts will have the wrong allowance value as it's tracked in nTokenTransferApproveAll but t...

TokenHandler.setToken ERC20 missing return value check

Handle cmichel Vulnerability details Vulnerability Details The setToken function performs an ERC20.approve call but does not check the success return value. Some tokens do not revert if the approval failed but return false instead. Impact Tokens that don't actually perform the approve and return...

CompoundToNotionalV2.enableToken ERC20 missing return value check

Handle cmichel Vulnerability details Vulnerability Details The enableToken function performs an ERC20.approve call but does not check the success return value. Some tokens do not revert if the approval failed but return false instead. Impact Tokens that don't actually perform the approve and retu...

CompoundToNotionalV2.notionalCallback ERC20 return values not checked

Handle cmichel Vulnerability details Vulnerability Details Some tokens like USDT don't correctly implement the EIP20 standard and their transfer/transferFrom function return void instead of a success boolean. Calling these functions with the correct EIP20 function signatures will always revert. S...

ERC20s that block transfer to particular addresses enable DoS/Censorship

Handle nascent Vulnerability details Tokens that prevent transfers to particular addresses most commonly address0 as is the OpenZeppelin standard enables DoS against a batch. If the attacker submits the bad transaction, the relayer wont submit the batch. The attacker never has to worry about the...

Freeze The Bridge Via Large ERC20 Names/Symbols/Denoms

Handle nascent Vulnerability details Ethereum Oracles watch for events on the Gravity.sol contract on the Ethereum blockchain. This is performed in the checkforevents function, ran in the ethoraclemainloop. In this function, there is the following code snippet: let erc20deployed = web3...

Reentrancy Bug in TimelockController.sol

Handle leastwood Vulnerability details Impact Notional's governance framework utilises a fork of Compound's Governor Alpha and ERC20 token. These are denoted specifically as the GovernorAlpha.sol and NoteERC20.sol contracts. However, the GovernorAlpha.sol has a key difference when compared to...

Arbitrary Logic Enables ERC20 Theft

Handle ElliotFriedman Vulnerability details Severe Issue: ERC20 Token Theft Using Arbitrary Logic There are 2 ways that this bug can be used to drain funds from the bridge. Both are catastrophic and result in total loss of funds. The 1st method is horrible, the second method is diabolical as it c...