DeFi Smart Contract Vulnerabilities Audit Guide

Here are three specific DeFi smart contract vulnerabilities suitable for inclusion in a professional audit report. Each entry includes the vulnerability class, a specific technical scenario, the root cause, and the potential impact.

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1. Reentrancy in Cross-Contract Calls (CWE-841)

Description:

Reentrancy occurs when a contract makes an external call to another contract (often a token contract) before updating its own state variables. If the external call triggers a callback into the vulnerable contract, an attacker can re-enter the function and drain funds before the original function completes its state update.

Specific Technical Scenario:

Consider a simplified lending protocol’s withdraw() function:

solidity
function withdraw(uint256 amount) external {
    require(balances[msg.sender] >= amount, "Insufficient balance");

    // VULNERABILITY: External call before state update
    (bool success