An unidentified investor attempted to exchange 50.43 million USDT for AAVE using the CoW Protocol aggregator and SushiSwap exchange. Ultimately, the investor received only 327 tokens valued at approximately $36,000.
The effective purchase price was approximately $154,000 per coin, although the market rate at the time was around $114.
An MEV bot, which monitors pending transactions in the mempool, exploited the situation. It executed a classic “sandwich attack”:
- secured a flash loan of $29 million in WETH on the Morpho platform;
- purchased a large volume of AAVE on Bancor, driving up the asset’s price;
- allowed the victim’s transaction to proceed, purchasing tokens at the inflated price;
- sold its tokens on SushiSwap, gaining a profit of $9.9 million.
User Responsibility
Aave founder Stani Kulechov stated that the protocol’s interface warned the investor of “critical slippage” due to the unusually large order. Despite this, the investor confirmed the transaction from a mobile device and agreed to the terms.
Earlier today, a user attempted to buy AAVE using $50M USDT through the Aave interface.
Given the unusually large size of the single order, the Aave interface, like most trading interfaces, warned the user about extraordinary slippage and required confirmation via a checkbox.…
— Stani.eth (@StaniKulechov) March 12, 2026
Kulechov emphasized that Aave will contact the user and reimburse them $600,000 in fees collected from the transaction.
CoW DAO also noted that the user saw warnings about the near-total loss of funds but consciously approved the transaction. According to the team, no DEX or aggregator could have executed such an order at a reasonable price.
Statement from CoW Protocol:
Earlier today, a trader attempted to swap 50M aEthUSDT for aEthAAVE through Aave’s swap interface, which is powered by CoW Protocol. Despite clear warnings that showed the user they would lose nearly all of the value of their transaction, and despite… https://t.co/Pav4udXUkX
— CoW DAO (@CoWSwap) March 13, 2026
“Such transactions highlight that the user experience in DeFi is not yet at the level required for the safety of all users. We are analyzing how to balance robust protection mechanisms with maintaining user autonomy. Needless to say, we will also return any fees from this transaction,” the developers added.
Back in April last year, an MEV bot intercepted $200,000 from participants in the Wayfinder PROMPT airdrop.
Ethereum co-founder Vitalik Buterin considers MEV one of the main issues threatening the network’s decentralization.