OpenSea paid damages for clients for $2 mln

An internal bug in the OpenSea platform allowed purchasing expensive NFTs at reduced prices. 

According to Bloomberg, users had to delist their assets themselves prior to the introduction of the urgent listing feature, which allowed tokens to be automatically de-listed after a certain period of time. This was a paid service that sometimes charged extremely high fees.  However, if the token was sent to the wallet and then sent back, it was no longer displayed in the marketplace, while the transaction was not registered in the blockchain. This made it possible to buy NFTs at old prices that were often much lower than the current ones. Using this vulnerability, one user managed to earn 347 ETHs by buying assets at a low price and immediately selling them at the current price. 

To fix the bug, the company notified customers to delist their cryto assets, and also reduced the length of NFT's listing on the marketplace from 6 months to one.