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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, described with the technical precision and structure required for a professional security audit report.

1. Reentrancy Attack via Unprotected External Calls

Vulnerability Type: Reentrancy

Severity: High

Affected Component: LendingPool.solwithdraw() function

Description:

The withdraw() function allows users to reclaim their deposited assets. The function performs an external call to the user’s wallet (msg.sender.transfer(amount)) before updating the internal balance mapping (balances[msg.sender] -= amount). This violates the Checks-Effects-Interactions (CEI) principle.

An attacker can exploit this by calling withdraw() from a malicious contract. When the external call is made, the attacker’s fallback function is executed, which can recursively call withdraw() again. Since the internal state has not yet been updated, the balance check passes once more, allowing the attacker to drain the

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