What Is the “Mempool” and Why Is Its Transparency a DEX Vulnerability?

The mempool (memory pool) is a waiting area for unconfirmed transactions on a blockchain network. All submitted transactions sit here before being picked up by a miner or validator and included in a block.

Its transparency is a DEX vulnerability because it allows anyone, particularly automated bots, to monitor pending, potentially large transactions and calculate the likely price impact. This public visibility enables the front-runner to quickly submit a counter-transaction with a higher gas fee to execute first and profit.