Balancer released a preliminary report on the v2 vulnerability attack incident on the X platform, disclosing that Balancer V2's composable stable pool was attacked on multiple chains (including Ethereum, Base, Avalanche, Polygon, Arbitrum, etc.) on November 4th. The vulnerability stemmed from a rounding logic error in the EXACT_OUT transaction within batchSwap. When the scaling factor is a non-integer value, this function rounds down, allowing attackers to manipulate pool balances and withdraw assets. This incident only affected Balancer V2's composable stable pool; Balancer V3 and other pool types were unaffected. The Balancer team, along with security partners and white-hat teams, acted swiftly, successfully containing the attack and recovering some assets through measures such as Hypernative automatic suspension, asset freezing, and white-hat intervention under the SEAL framework. Balancer added that it is currently working with security partners such as SEAL and zeroShadow on cross-chain tracing and fund recovery, and the final verified loss and recovery data will be published in a full technical review report. The official reminder to users: Only obtain confirmation information through official Balancer channels. V3 and unstable pool operations remain safe.