Umbrella Network's Polar Stream staking contracts on Ethereum and BSC suffered an unchecked underflow in the withdrawal function. The attacker drained LP tokens and used them to withdraw liquidity from UMB-ETH Uniswap and UMB-BNB Pancakeswap pools.

DeFi oracle Umbrella Network’s Ethereum and BNB Chain (formerly BSC) reward pools were hacked, resulting in the hackers earning around $700,000. The hacker was able to succeed because of an unchecked vulnerability in withdraw() , so anyone could withdraw any amount of funds without having any balance.