$ETH An unknown attacker prompted Ethereum developers to roll out a “private fix” as the network grappled with technical issues during the Pectra upgrade on the Sepolia testnet.

In a post-incident report, Ethereum developer Marius van der Wijden revealed that the attacker exploited an overlooked “edge case,” repeatedly triggering errors by sending zero-token transfers to the deposit contract, further complicating an already troubled rollout.