Hackers used a vulnerability in Uniswap and ERC777 to launch an attack. The capital in dForce Foundation dropped by 99.9%! Lendf.me has lost more than $24.5 million in funds. Hackers use an exploit published on GitHub in July 2019 by OpenZeppelin, a company that performs security checks for cryptocurrency platforms. The combination of the use of ERC-777 tokens and Unis wap/Lendfme made the reentrancy attacks possible.