Hackers Steal Over $120 Million From DeFi Protocol Balancer Amid Security Flaws

The decentralized finance protocol Balancer suffered a major security breach affecting its V2 Composable Stable Pools, resulting in losses exceeding $120 million. The exploit stemmed from vulnerabilities including a precision rounding error in Vault swap calculations and improper authorization and callback handling, which attackers exploited to manipulate swaps and drain assets rapidly. Despite Balancer's history of extensive audits and previous security incidents, this attack caused its total value locked to halve in a single day. The Balancer team responded promptly by pausing affected pools, collaborating with security researchers, and offering a white-hat bounty to recover stolen assets, with some funds already recovered by external parties. The incident led to increased caution across related platforms, with some freezing operations to protect assets. Balancer continues to investigate the breach and plans to release a thorough post-mortem to clarify the attack's precise mechanics and prevent future occurrences.