MEV & The Dark Forest

When you submit a swap on a DEX with high slippage, your transaction sits in the public mempool.

Searchers can scan a public mempool and attempt a sandwich: buy before a vulnerable swap, let it execute at a worse price within its tolerance, then sell afterward. The attempt is not risk-free; competition, reordering, failed inclusion, fees, price movement, and private order flow can make it fail or lose money.

Protection is a routing and transaction-design problem. Tight tolerances can cause failed swaps in volatile or thin pools; private submission changes who can observe the order but introduces builder or relay assumptions; intents and batch auctions have their own trust and execution models. Compare expected price, minimum received, gas, route, and failure behavior before signing.