Devs Group Discover Major Ethereum Flaw; Freezes Transactions for 12 Secs

Last week, the newly formed Special Mechanisms Group (SMG) showed how to use a feature of the proposer-builder separation market to push through only their own transaction in Ethereum.

By decoupling the responsibilities of block builders and block proposers on the perpetually growing Ethereum blockchain, proposer-builder separation (PBS) aims to make the network more resistant to censorship. The developers group, however, figured out how to publicly exploit this flaw.

Community Taken by Surprise

In the lone transaction on the block, a link was included to a presentation and research paper on SMG’s website that detailed the issue and offered solutions. The community was taken by surprise by how simple it was for someone to freeze transactions.

Wont Work for Long Though

Former Augur software engineer Ryan Berckmans was among those who noted that this method of delaying transactions wouldn’t work for very long due to Ethereum’s gas fee market, but that it did highlight some issues with the way some applications on Ethereum calculate the gas fees required to get transactions included in a block.

Since Ethereum is supposed to be “credibly neutral,” it’s concerning when user transactions might be excluded from a block. Technically, after the Merge, they were known as “slots,” however either name may be used interchangeably.

To most people, “censorship” means permanently blocking a transaction, not just delaying it temporarily. It’s also not an entirely novel issue. As for the SMG, they don’t agree.

The group stated:

“When bidders in an auction, or agents in a financial system can censor their competition, the efficiency of these systems erodes,” they tweeted. “In other words, censorship-resistance is about more than just ensuring a transaction gets on-chain ‘eventually.’ It needs to be fast.”

Enough Time to Cause a Problem

Max Resnick, director of research at SMG and one of the paper’s authors, said that “we are more worried about 12 seconds being enough time to cause a problem than 10 mins,” adding that he believes the critics exaggerate the expense of expanding the waiting period any more.

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Yet, “there are a lot of useful mechanisms (like auctions) that we can’t build on chain because it would be easy for participants to censor their competition’s bids,” Resnick noted, even on a short timeline. He argued that not all use cases could make the transition to layer-2s, but that many could.