F-2025-0003·missing-zero-check
Zero-Value Fee Transfers Can Revert
TL;DR
Some ERC-20 tokens (like LEND) revert on zero-value transfers. The contract attempts the fee transfer without checking whether the fee amount is zero, blocking very small payments.
Severity
LOW
Impact
LOW
Likelihood
MEDIUM
Method
MManual review
CAT.
Complexity
LOW
Exploitability
LOW
02Section · Description
Description
Some ERC-20 tokens (like LEND) revert on zero-value transfers. The contract doesn't check if the fee amount is zero before attempting the transfer:
solidity
function _createERC20Payment(...) internal {(uint256 feeAmount, uint256 paymentAmount) = _processFee(amount);// feeAmount could be 0 for very small paymentsSafeERC20.safeTransfer(token, feeRecipient, feeAmount);}
03Section · Impact
Impact
- Payments with very small amounts where fee rounds to zero will revert.
- Users cannot create small payments.
- Wastes gas on failed transactions.
- Poor user experience.
04Section · Recommendation
Recommendation
The recommended approach is to add a zero-check in the function before transfer:
solidity
function _createERC20Payment(...) internal {(uint256 feeAmount, uint256 paymentAmount) = _processFee(amount);if (feeAmount > 0) {SafeERC20.safeTransfer(token, feeRecipient, feeAmount);}}
