Ethereum developers: Attackers can use the free testnet ETH to win Sepolia block auctions and withhold transaction payloads

Ethereum developers warn: Attackers can exploit free testnet ETH and one-time builder identities to win Sepolia block auctions and withhold transaction payloads during the Glamsterdam testing period.

This attack does not threaten mainnet funds but may disrupt infrastructure testing. The Sepolia public test is scheduled to launch on October 6, with the Hoodi test tentatively set for October 27, and the mainnet activation time is still undetermined.