Sandwich Attack.

A form of MEV in which an attacker places a buy order before a victim's pending swap and a sell order immediately after, profiting from the artificial price move they induce. It belongs to the Web3 & Blockchain category of cybersecurity.

A form of MEV in which an attacker places a buy order before a victim's pending swap and a sell order immediately after, profiting from the artificial price move they induce.

Sandwich attacks target swaps on automated market makers (AMMs) such as Uniswap, SushiSwap, or PancakeSwap. The attacker spots a large pending swap in the public mempool that will move the pool's price. They submit a front-running buy of the same asset with higher gas, the victim's swap then executes at a worse price because of the moved curve, and the attacker immediately back-runs with a sell at the new inflated price. The victim suffers extra slippage; the attacker pockets the difference minus gas. Defences include tight slippage tolerances, private order flow (Flashbots Protect, MEV-Share), batch auctions like CoW Swap, and routing aggregators that split orders.

Defences for Sandwich Attack typically combine technical controls and operational practices, as detailed in the full definition above.

Common alternative names include: AMM sandwich, Sandwich MEV.