Reentrancy Attacks

Definition ∞ Reentrancy attacks are a critical vulnerability in smart contracts where an external contract call can repeatedly call back into the original contract before the initial execution finishes. This allows an attacker to drain funds or manipulate contract state by bypassing intended checks or balances. The most infamous example is the DAO hack, which resulted in a major blockchain split. Preventing reentrancy requires careful coding practices and security audits. Such exploits pose a severe threat to contract security.
Context ∞ Reentrancy attacks remain a significant security concern in the decentralized finance (DeFi) sector, frequently reported in news about smart contract exploits. Developers use “checks-effects-interactions” patterns and reentrancy guards to mitigate this risk. The continuous evolution of attack vectors necessitates constant vigilance and the adoption of robust security frameworks in smart contract development.