The proposal aims to give XRPL users guaranteed execution priority if they pay a reservation fee before a ledger closes.
David Schwartz, who co-founded the XRP Ledger, has proposed a transaction reservation scheme as a potential fix for front-running on the network’s decentralized exchange and automated market maker.
His proposal was in response to a post from the XRP-focused account XRPresso.io, which argued that validators and well-connected nodes can exploit pre-validation transaction visibility to extract value from regular traders.
Front-Running Concerns on XRPL
According to XRPresso, transfers usually sit in a publicly visible queue before a ledger closes on the XRPL, with validators and some nodes able to see these pending trades. As such, they are in a position to assess whether sandwiching them would be profitable, and then to submit multiple entries to game their position in the final canonical ordering.
And because that ordering is decided by a known, deterministic formula involving transaction hashes, submitting similar entries increases the odds of landing in a favorable slot relative to the target trade. That, as XRPresso claimed, could see everyday users trading through standard wallets and apps getting systematically disadvantaged while more sophisticated operators extract value from their trades.
Schwartz acknowledged that the issue is real but pushed back on parts of the framing. He pointed out that all participants have an equal opportunity to see transfers and argued that validators don’t gain any structural advantage unless several of them conspire. Such an action, he said, would be visible on-chain and lead to the removal of the offending validators from the trust lists.
“If multiple validators did conspire, or a single validator attempted it, it would be *very* obvious to everyone exactly who was doing this,” he wrote.
Furthermore, he said that there have never been any reports of anyone attempting something like that, except as a proof of concept. The biggest issue, according to him, has been profitability, since to make money, the actors would need both high liquidity that would make volumes worth the effort available and low liquidity to move the price measurably and at a reasonable cost.
Still, he offered a solution in which a user would submit a reservation transaction specifying a ledger sequence number and a transaction ID, and pay a reservation fee. If the reservation succeeds and the actual activity is broadcast before that ledger closes, it gets guaranteed priority over any other formed after the original was disclosed.
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“This guarantees that you can execute your transaction ahead of any transaction that was formed after your transaction was disclosed,” explained the developer. “You would use this approach any time you want to perform a transaction that you want to ensure cannot be sandwiched or front run.”
The Front-Running Debate in DeFi
XRPresso responded that while Schwartz’s reservation idea is worth exploring, it would add cost and complexity and does not fully address the underlying visibility problem in the pre-validation stage. According to them, targeted confidentiality for the details of pending actions would be a cleaner long-term fix, with such approaches already being used on other chains.
The front-running problem isn’t unique to the XRP ecosystem, and Binance co-founder Changpeng Zhao proposed a dark pool perpetuals DEX last year that uses zero-knowledge cryptography to hide order data until execution. That idea drew criticism too, with some decentralization advocates claiming that hiding order books will just recreate the insider dynamics that crypto was meant to move away from.
