MakerDAO

During the March 12 ETH crash (43% in one day), the Maker Medianizer oracle failed to update due to network congestion and high gas fees, leaving the system with stale prices. Liquidators exploited this by bidding zero DAI for collateral worth millions, acquiring 62K ETH for free.

36% of liquidations resulted in zero-bid auctions, causing a $6M DAI shortfall and $4M bad debt before governance intervention.