A teenager with free test ether and a collection of disposable builder identities could repeatedly win Ethereum’s new block auctions and refuse to deliver the transactions, developers warned as they confirmed an Oct. 6 public test of the Glamsterdam upgrade.
The attack would not endanger mainnet funds. It targets Sepolia, where test ether has no meaningful cost, but could leave blocks without transaction payloads and derail the infrastructure testing needed before Glamsterdam reaches Ethereum itself.
Glamsterdam moves the relationship between validators and specialized block builders into Ethereum’s protocol. Builders assemble transaction blocks and compete to supply them. Once a validator accepts the winning bid, the builder is expected to reveal the underlying transactions.
That process becomes easy to abuse on a free test network. A malicious operator can submit bids far above every legitimate builder, win repeatedly and then…
