Poly Network was exploited for $611M on August 10, 2021 across Ethereum ($273M), BSC ($253M) and Polygon ($85M) via an access control and cryptography vulnerability in cross-chain bridge contracts. The attacker voluntarily returned nearly all funds within 15 days, keeping only transaction fees.

Poly Network, a cross-chain interoperability protocol, said it was attacked, and a total of more than 610 million US dollars were transferred to 3 addresses. Among them, the funds transferred to Binance smart chain addresses starting with 0x0D6e2 exceeded 250 million US dollars, and they were transferred to the ether starting with 0xC8a65. There are over 270 million U.S. dollars in workshop addresses, and over 85 million U.S. dollars in transfers to Polygon addresses. Affected by this, the large amount of assets in the O3 Swap cross-chain pool was transferred out, and the official is investigating.With the efforts of many parties, the hackers have now returned tokens worth 342 million U.S. dollars.