Skip to main content

Unbounded Loop

What it detects​

Loops without explicit bounds can grow with user input or contract state, consuming all available gas and causing transactions to fail. The detector searches for for or while statements lacking clear termination conditions.

Typical symptoms​

  • Loop uses array length that user can expand
  • No maximum iteration count enforced

Solidity snippet (v0.8.25)​

pragma solidity ^0.8.25;

contract Endless {
    uint256[] public list;

    function sum() external view returns (uint256 s) {
        for (uint256 i = 0; i < list.length; i++) {
            // list length may be unbounded
            s += list[i];
        }
    }
}

Why it matters on EVM​

Unbounded loops can halt contract functions and enable denial-of-service attacks if they run out of gas.