On March 15-16, 2022, an attacker exploited a reentrancy vulnerability in Hundred Finance's callback handling to borrow $6 million across multiple markets. The attacker deposited ~$2M USDC collateral, then repeatedly borrowed against it via the onTokenTransfer() callback which triggered before debt was updated.

Hundred Finance, the Compound fork project on the Gnosis chain, tweeted that it suffered a hacker attack and lost more than $6 million.