सबसे Common Solidity Vulnerabilities

# सबसे Common Solidity Vulnerabilities

Smart contracts की security paramount है। यहाँ 2026 में सबसे frequent 10 vulnerabilities हैं, vulnerable code और solutions के साथ।

1. Reentrancy

Risk: State update से पहले recursive call।

// ❌ VULNERABLE
function withdraw(uint amount) public {
    require(balances[msg.sender] >= amount);
    (bool success,) = msg.sender.call{value: amount}("");
    balances[msg.sender] -= amount; // बहुत late!
}

// ✅ SECURE
function withdraw(uint amount) public {
    require(balances[msg.sender] >= amount);
    balances[msg.sender] -= amount; // पहले effect
    (bool success,) = msg.sender.call{value: amount}("");
    require(success);
}

2. Access Control

Risk: Critical functions बिना restriction के।

// ❌ VULNERABLE
function mint(address to, uint amount) public {
    balances[to] += amount;
}

// ✅ SECURE
address public owner;
modifier onlyOwner() {
    require(msg.sender == owner);
    _;
}

function mint(address to, uint amount) public onlyOwner {
    balances[to] += amount;
}

3. Integer Overflow (pre-0.8.0)

Solidity 0.8.0 से, automatic protection। लेकिन unchecked blocks पर ध्यान दें!

4. Timestamp Manipulation

Risk: Miners block.timestamp manipulate कर सकते हैं (±15 seconds)।

// ❌ randomness के लिए VULNERABLE
function random() public view returns (uint) {
    return uint(keccak256(abi.encodePacked(block.timestamp)));
}

// ✅ Oracle use करें (Chainlink VRF)

5. tx.origin for Auth

Risk: tx.origin को phishing via exploit किया जा सकता है।

// ❌ VULNERABLE
function withdraw() public {
    require(tx.origin == owner);
    // Phishing possible!
}

// ✅ SECURE
function withdraw() public {
    require(msg.sender == owner);
}

निष्कर्ष

इन vulnerabilities को detect करने के लिए Slither, Foundry fuzz testing और professional audits use करें।

Solingo पर हमारे 60 security challenges के साथ practice करें!