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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 security audit reports, detailed with technical context, impact, and remediation guidance:

1. Reentrancy in Shared State Variables

Description:

Reentrancy occurs when an external call to another contract allows the attacker to re-enter the vulnerable function before the state of the current execution is updated. While classic reentrancy in single-function storage updates is well-known, cross-function reentrancy (or "state update after external call") in complex DeFi protocols is a critical variant.

Specific Example:

A staking contract has a withdraw() function that:

  1. Checks user balance.
  2. Sends ETH to the user via call{value: amount}().
  3. Updates the user’s balance in storage.

If the user is a malicious contract, the call triggers the attacker’s receive() or fallback() function, which re-calls

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