Bridge Incident Registry
Incident case

Poly Network 2021 cross-chain exploit

In August 2021, Poly Network was exploited for more than $600 million across multiple chains. The case became a major reference point because the attacker later returned most or all of the funds, making it a recovery-centered bridge incident rather than a permanent-loss case.

reviewedcurrent

Incident facts

Incident title
Poly Network 2021 cross-chain exploit
Bridge
Poly Network
Incident date
2021-08-10
Incident type
Exploit
Major incident
Yes
Affected chains
Ethereum, BNB Chain, Polygon
Affected assets
ETH, USDC, USDT, WBTC, BNB, MATIC
Attack category
Cross Chain Contract Exploit
Reported loss
$610 million
Recovery
Full Recovery
Reimbursement
Not Applicable
Restart
Reopened
Current outcome
Active After Incident
Resolution
Final outcome known
Last reviewed
2026-07-28
Last verified
2026-07-28

Timeline events

  • Stolen funds returned in stages2021-08

    The attacker returned the stolen assets in stages after communicating publicly with Poly Network and the wider crypto community.

    Funds ReturnedHigh

  • Poly Network exploit disclosed2021-08-10

    Poly Network disclosed a cross-chain exploit involving assets valued at more than $600 million across multiple networks.

    Exploit DisclosedHigh

  • Poly Network upgraded mainnet and began restoring cross-chain service2021-08-16

    Poly Network reported that its upgraded mainnet was live and cross-chain functionality had begun returning for supported assets under a staged restoration process.

    Bridge Partially ReopenedHigh

  • Recovery treated as substantially complete2021-09

    Later reporting treated the Poly Network case as a near-complete or complete recovery of the stolen funds, distinguishing it from permanent-loss bridge incidents.

    Recovery CompletedMedium

  • Poly Network completed its operations-resumption roadmap2021-09

    Poly Network later reported that the roadmap for resuming operations and restoring user assets had been completed, after cross-chain services and advanced functions were progressively restored.

    Bridge ReopenedHigh

Evidence records

Known unknowns