Top 10 Smart Contract Vulnerabilities in 2025

Introduction

Smart contract vulnerabilities have cost the crypto industry billions of dollars. Understanding these vulnerabilities is the first step to preventing them.

Top 10 Vulnerabilities

1. Reentrancy Attacks

The classic vulnerability that caused the DAO hack. Always use the checks-effects-interactions pattern.

2. Integer Overflow/Underflow

While Solidity 0.8+ has built-in overflow checks, many legacy contracts remain vulnerable.

3. Access Control Issues

Improper access control allows unauthorized users to call privileged functions.

4. Flash Loan Attacks

Attackers use flash loans to manipulate prices and exploit vulnerabilities in a single transaction.

5. Oracle Manipulation

Price oracles can be manipulated if not properly secured, leading to massive losses.

6. Front-Running

Transactions can be front-run by miners or bots who see pending transactions in the mempool.

7. Denial of Service

Contracts can be made unusable through various DoS attack vectors.

8. Logic Errors

Simple programming mistakes in business logic can lead to fund losses.

9. Signature Replay

Signatures can be replayed across different chains or contexts if not properly protected.

10. Unchecked External Calls

External calls that fail silently can leave contracts in inconsistent states.

Prevention

The best prevention is a professional smart contract audit. At Audit911, we offer comprehensive audits at industry-lowest prices.