uToken's approve() Function is Susceptible to Frontrunning Attacks

Handle leastwood Vulnerability details Impact Order makers will call the approve function to facilitate transactions between order takers and makers. If a taker sees that a maker is seeking to reduce its order exposure by reducing Swivel.sol's allowance, a taker can frontrun this transaction to...

Markets Do Not Operate Correctly on Non-Standard Tokens

Handle leastwood Vulnerability details Impact There are a number of functions which interact with uToken in Swivel.sol but do not check the return value of the associated transfer, approve or transferFrom call. As a result, if a market is created using a non-standard token, a failed call will be...

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...

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.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.approve() return value is ignored

Handle pants Vulnerability details According to the ERC-20 Token Standard, the function approve returns false on failure. However, the return value of Erc20.approve is ignored 3 times: 1. In Swivel.initiateVaultFillingZcTokenInitiate, line 109. 2. In Swivel.initiateZcTokenFillingVaultInitiate, li...

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.transfer() return value is ignored

Handle pants Vulnerability details According to the ERC-20 Token Standard, the function transfer returns false on failure. However, the return value of Erc20.transfer is ignored 8 times: 1. In Swivel.exitVaultFillingZcTokenExit, line 313. 2. In Swivel.exitVaultFillingZcTokenExit, line 315. 3. 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...

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...

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...

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...

TokenHandler.safeTransferIn does not work on non-standard compliant tokens like USDT

Handle cmichel Vulnerability details Vulnerability Details The TokenHandler.safeTransferIn function uses the standard IERC20 function for the transfer call and proceeds with a checkReturnCode function to handle non-standard compliant tokens that don't return a return value. However, this does not...

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...

TokenHandler.safeTransferOut does not work on non-standard compliant tokens like USDT

Handle cmichel Vulnerability details Vulnerability Details The TokenHandler.safeTransferOut function uses the standard IERC20 function for the transfer call and proceeds with a checkReturnCode function to handle non-standard compliant tokens that don't return a return value. However, this does no...

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...

Use safeTransfer instead of transfer

Handle shw Vulnerability details Impact Tokens not compliant with the ERC20 specification could return false from the transfer function call to indicate the transfer fails, while the calling contract would not notice the failure if the return value is not checked. Checking the return value is a...

No ERC20 safe* versions called

Handle cmichel Vulnerability details The claim function performs an ERC20 transfer rewardsToken.transferto, claiming; but does not check the return value, nor does it work with all legacy tokens. Some tokens like USDT don't correctly implement the EIP20 standard and their transfer/transferFrom...

Use safeTransfer instead of transfer

Handle shw Vulnerability details Impact Tokens not compliant with the ERC20 specification could return false from the approve call to indicate the approval fails, while the calling contract would not notice the failure if the return value is not checked. Proof of Concept Referenced code:...

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 Staker.withdraw function does not chec...