Solana Heavyweights Wage War Against Private Mempool Operators

A group of Solana (SOL) validators is facing significant penalties for allegedly facilitating economic attacks against crypto traders. Over the weekend, more than 30 validator operators were removed from the Solana Foundation Delegation Program, according to a source familiar with the matter. Although these operators remain validators on the network, they are no longer eligible for payout boosters that come from validating transactions on the Solana blockchain. Many of these operators are reportedly from Russia.

This crackdown marks an escalation in the ongoing conflict between major players in the Solana validator ecosystem and an underground network of validators accused of exploiting traders through sandwich attacks. In these attacks, bots front-run and backfill trades that haven’t yet been executed, taking advantage of traders.

Sandwich attacks are a form of maximal extractable value (MEV) strategy, which is notorious on blockchains that use mempools—essentially waiting rooms for unconfirmed transactions. Solana doesn’t have a native mempool, but the widely used validator software developed by Jito Labs once did.

In March, amid a surge in meme coin trading on Solana, Jito Labs disabled the mempool function due to the prevalence of sandwich attacks. Jito’s CEO stated that the decision was made to protect the Solana ecosystem, even though it eliminated a potential revenue stream for validators, the server operators that maintain the decentralized network.

However, this move didn’t completely eliminate the problem; it pushed it underground. Reports soon surfaced about private mempools whose operators were making significant profits from enabling sandwich attacks. One proposal from infrastructure operator DeezNode offered validators participating in its private mempool 50% of the profits generated by MEV, according to documents.

A Jito Foundation governance post from late Sunday indicated that 10% of the JitoSOL pool is being delegated to validators running private mempools. The Jito Foundation has proposed further economic penalties on these validators by restricting even more staked SOL.

The Solana Foundation’s own delegation blacklist is relatively small within the context of the entire delegation program. It targets 32 operators that collectively held 1.5 million SOL, about 0.5% of the program’s stake, a source said.

“Enforcement actions are ongoing as we detect operators participating in mempools which allow sandwich attacks,” a representative for the Solana Foundation stated on Sunday.