Ethereum's cross-chain bridge technology has advanced, but it remains vulnerable to complex attack vectors. Bridges like Arbitrum and Optimism use optimistic rollups, while others like Polygon employ sidechains, each with distinct security models. Common risks include smart contract bugs, oracle manipulation, and 51% attacks on connected chains. Recent incidents, such as the Ronin bridge exploit, highlight vulnerabilities in validator consensus and private key management. While solutions like multi-signature wallets, time-locks, and formal verification improve resilience, no bridge is immune to sophisticated attacks. Zero-knowledge proofs and decentralized oracles are promising but not foolproof. Ensuring robust audits, bug bounties, and rapid response mechanisms is critical to mitigating risks.