F-2025-0003·missing-zero-check

Zero-Value Fee Transfers Can Revert

Acknowledgedescrowpaymentserc-20

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 payments
    SafeERC20.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);
    }
}