DeFi Protocols Lose Billions Annually to Hacks: Key Vulnerabilities Explained

Decentralized finance (DeFi) protocols, built on public blockchains using smart contracts, have attracted trillions of dollars in value since pioneers like MakerDAO, Compound, and Uniswap emerged around 2018–2020. However, billions of dollars are drained from these protocols every year through a range of exploits, according to blockchain security firms such as Chainalysis and PeckShield. Core vulnerabilities include flaws in smart contract code — such as reentrancy attacks, logic errors, and access control weaknesses — that allow bad actors to manipulate protocol behavior or siphon funds. External data feeds known as oracles are also frequently targeted, with attackers manipulating asset prices on low-liquidity exchanges to exploit lending or liquidation mechanisms. The open-source and composable nature of DeFi, while fostering innovation, amplifies these risks by exposing entire codebases to scrutiny and allowing a single vulnerability in one protocol to cascade across interconnected systems.