Early access to Solana user transactions is under scrutiny following application complaints about front-running and sandwich attacks, which Jito Labs co-founder Lucas Bruder said coincided with greater use of transaction auctions.
Bruder put the share of staked Solana (SOL) involved in some form of order-flow auction at 30% to 40%. He said applications and other network participants brought their concerns to Jito Labs in recent months, as validator and client teams made greater use of the arrangements.
In the arrangements Bruder described, validators give outside searchers an early view of user transactions in exchange for a share of the resulting revenue. He characterized that access as a private mempool. The revenue gives validators an incentive to offer access, while selected searchers get information ahead of others.
Bruder alleged that weak oversight at one provider allowed searchers to mount sandwich attacks on several applications over a period of weeks. He said affected users received no compensation.
Auction providers cite identity checks and safeguards against front-running, Bruder said. He questioned whether those safeguards could be assessed as effective before abuse came to light and users suffered losses.
Jito shut its public mempool in March 2024 after sandwich attacks. Bruder’s current concerns focus on early transaction access through auctions.
The Fidelity Center for Applied Technology (FCAT) found that about 63% of Solana’s active stake ran Jito configurations in the third quarter of 2026, as earlier coverage of Solana validator concentration detailed. That figure measures validator configurations by active stake, not participation in order-flow auctions. Bruder’s 30% to 40% figure is an estimate of auction participation.
Bruder urged validators to examine whether their software gives outsiders an early view of transactions. He also said people delegating stake should consider transaction execution quality when weighing staking returns.
