On November 3, 2025, Balancer suffered an incident in which attackers manipulated internal vault logic to drain liquidity across multiple blockchains. The breach underscores the importance of prioritizing security even for mature protocols with multiple audits, and it raises urgent questions about composability, operational controls, and the evolving threat-landscape in Web3. Here is Certora’s analysis of the incident, as well as a detailed timeline of events.

In recent years, tiny rounding mistakes, often as small as 1 wei, have cost DeFi protocols over $100 million. Because the EVM only handles integers, every division forces a round‑up or round‑down decision, creating subtle gaps that attackers can exploit at scale. Learn how formal verification tools can systematically prove your contracts’ invariants and reveal hidden rounding bugs before they go live.