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Unchecked Math

What it detects​

The detector highlights arithmetic enclosed in unchecked blocks or low-level assembly that sidesteps Solidity's built-in safety checks. Without these checks, overflow or underflow can occur silently.

Typical symptoms​

  • unchecked { ... } surrounding math operations
  • Comments referencing gas savings at the expense of safety

Solidity snippet (v0.8.25)​

pragma solidity ^0.8.25;

contract SkipChecks {
    function mul(uint256 a, uint256 b) external pure returns (uint256) {
        unchecked {
            // No overflow check performed
            return a * b;
        }
    }
}

Why it matters on EVM​

Unchecked arithmetic can introduce hidden overflows or underflows, leading to serious accounting errors and exploitable states.