Missing zero-address check

Severity: Low ID: missing-zero-check

Flags entry-point functions and constructors where an address parameter flows into a state write or value transfer without a zero-address guard.

What it does

Performs a taint analysis from each address parameter of an externally callable, state-mutating function (or constructor) and reports a parameter that reaches a sink (state write, transfer, call{value: ...}, etc.) without first being compared against address(0) in an if/require/ assert predicate.

Why is this bad?

Forgetting a zero-address check is a common source of value loss: tokens become permanently unrecoverable, ownership is renounced unintentionally, or upgrades are bricked. Adding an explicit guard is cheap and removes an entire class of operational mistakes.

Example

Bad

function setOwner(address newOwner) external onlyOwner {
    owner = newOwner; // no zero-address check
}

Good

function setOwner(address newOwner) external onlyOwner {
    require(newOwner != address(0), "zero address");
    owner = newOwner;
}