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Nexus Intelligence Research
Nexus Intelligence Research

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DeFi Smart Contract Vulnerabilities Audit Guide

Here are three specific DeFi smart contract vulnerabilities commonly identified in professional audit reports, described with technical precision suitable for inclusion in a formal security assessment.

1. Reentrancy Vulnerability in Non-Atomic State Updates

Description:

This vulnerability occurs when a smart contract performs an external call (e.g., sending ETH to another contract) before updating its internal state variables. If the external contract is malicious, it can re-enter the vulnerable function before the state update completes, allowing repeated withdrawals or state manipulation.

Specific Example:

A withdraw() function in a lending protocol executes the following logic:

  1. Calculates the user’s withdrawal amount.
  2. Sends ETH to the user via address payable(user).transfer(amount).
  3. Updates the user’s balance in the contract’s storage: balances[user] -= amount.

Exploit Vector:

A malicious contract calls withdraw(). During the transfer() call, the malicious contract’s

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