Balancer Links $128M Multi-Chain Exploit to Rounding Error in Swap Logic

Balancer issued a preliminary incident report on the November 3 exploit that drained over $128 million from Composable Stable Pools across nine networks. The protocol identified a rounding flaw in its v2 vault's batchSwap feature as the root cause, which attackers exploited to manipulate pool balances and extract value. Balancer v3 and other pool types remained unaffected.