Balancer V1 Legacy Pools: A Rounding Error Costs $234,000, and Nobody Can Pause the Pools

If you have liquidity sitting in an old Balancer V1 pool, you have to withdraw it yourself. Nobody can pause those pools for you. On August 31, 2026 Balancer called on liquidity providers to exit the retired V1 pools, after an attacker had drawn roughly $234,000 out of one of them through a rounding error. The contracts date from 2020, they cannot be paused, and the company that once built them has not existed since spring 2026. The exit therefore rests entirely with you. We measured the situation ourselves on the Ethereum blockchain on September 1, 2026, rather than assembling it from reports. What came out of that is set out further down: the affected pool is effectively empty, the function that was attacked is still sitting in the contract, and the factory that produces such pools is running unchanged. What happened in the Balancer V1 pool on August 31: $234,000 through a rounding error On August 31, 2026 a liquidity pool built to the Balancer V1 design lost around $234,000, according to an analysis by the security firm SlowMist. The pool held four assets, among them Wrapped Bitcoin (WBTC), the form of Bitcoin represented on Ethereum. The attacker needed no stolen keys and no ba...