Solidity

[Mercure28]

How to avoid security vulnerabilities like Reentrancy Attack in a Solidity smart contract?

[TatyOko28]

A reentrancy attack occurs when a contract calls another contract before completing its execution, allowing the malicious contract to re-execute certain parts of the code in unexpected ways.

Solution :

Use Checks-Effects-Interactions scheme (modify variables first before sending ETH).
Use ReentrancyGuardOpenZeppelin

import "@openzeppelin/contracts/security/ReentrancyGuard.sol";
contract MyContract is ReentrancyGuard {
    function withdraw(uint amount) external nonReentrant {
        require(balance[msg.sender] >= amount, "Not enough balance");
        balance[msg.sender] -= amount;
        payable(msg.sender).transfer(amount);
    }
}