What are the security risks associated with smart contracts?

Smart contracts are self-executing programs on blockchain networks like Ethereum. Security risks include: bugs in code that hackers can exploit (e.g., the 2016 DAO hack cost $50 million), reentrancy attacks where functions are called repeatedly before updates complete, and integer overflow/underflow errors. Additionally, developers may introduce vulnerabilities unknowingly, and once deployed, contracts typically cannot be modified. Users should verify contracts are audited by reputable firms, check deployment history, and start with small amounts. Even well-known projects can have issues—the Ronin bridge hack in 2022 lost $625 million due to compromised validator keys. Always research before interacting with new smart contracts.