Morning Edition · Thursday, July 9, 2026Published at 1:30 AM EDT · New York

Ethereum Researchers Warn Block Builders Can Quietly Steal Searchers' Trades

Under proposer-builder separation, a single builder sees every bundle before assembling a block and can replicate a profitable one instead of honoring it.

A new Ethereum Research post argues that proposer-builder separation (PBS), the design that splits the job of ordering transactions from the job of proposing blocks, carries an incentive flaw that the system does not currently constrain. Un…