Delegatecall inside payable loop

Severity: Low ID: delegatecall-loop

Flags delegatecall operations inside loops in externally callable payable functions.

What it does

Reports delegatecall expressions that appear in the body of a for, while, or do while loop when the enclosing function is public payable or external payable.

Why is this bad?

delegatecall executes another contract's code in the caller's storage context and preserves the original msg.sender and msg.value. In a payable function, a loop can therefore expose the same msg.value to multiple delegatecalls even though Ether was only transferred once.

If the delegated code accounts for msg.value, one transaction can credit the same payment multiple times or repeatedly mutate the caller's storage in unexpected ways.

Example

Bad

function batch(address[] calldata receivers) external payable {
    for (uint256 i; i < receivers.length; ++i) {
        address(this).delegatecall(abi.encodeWithSignature("credit(address)", receivers[i]));
    }
}

Good

function batch(address[] calldata receivers) external payable {
    uint256 share = msg.value / receivers.length;
    for (uint256 i; i < receivers.length; ++i) {
        _credit(receivers[i], share);
    }
}

Notes

Review each occurrence manually. If delegatecall is required, ensure delegated code cannot reuse msg.value or unexpectedly modify caller storage across loop iterations.