Competing accounts of DeFi’s largest execution loss expose compounding infrastructure failures and a possible mempool leak.
Posted March 16, 2026 at 7:28 am EST.
Aave’s worst week in recent memory now has competing explanations. On Saturday, both Aave and CoW Swap released their own autopsies of the March 12 incident in which a user converted $50.4 million in aEthUSDT into roughly $36,000 worth of AAVE tokens, what many are calling the largest single-trade execution loss DeFi has ever seen.
The narratives split on responsibility. Aave pinned the outcome on thin liquidity, pointing out that the user confirmed a 99.9% price impact warning on a mobile device before proceeding. CoW Swap’s account was far grimmer: legacy code enforcing a stale gas ceiling filtered out better-priced quotes, a top-performing solver won back-to-back auctions yet never broadcast either transaction to the chain, and blockchain evidence points to the trade leaking from a private mempool, likely enabling the roughly $34 million in value that block builder Titan Builder captured.
This story is an excerpt from the Unchained Daily newsletter.
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The blowup compounds an already bruising stretch for the $26 billion protocol. An oracle misconfiguration two days prior had forced $26 million in wrongful wstETH liquidations, and a months-long governance fight over swap fee transparency recently pushed out the Aave Chan Initiative, the DAO’s most prolific contributor.
Aave’s fix is “Aave Shield,” a default block on any swap exceeding 25% price impact. CoW Swap went further in self-examination, conceding that a confirmation checkbox amounts to little when $50 million is on the line.
