Nomad hack — August 2022

Nomad's token bridge was emptied on 1 August 2022 through an initialisation error introduced in a routine upgrade deployed on 21 June 2022. Nomad's own root cause analysis sets out the flaw: the Replica contract's message authentication was changed to test status with acceptableRoot(), and Replicas deployed alongside their Home contracts were initialised with a committed root of bytes32(0), which set confirmAt[bytes32(0)] = 1. Any message that had never been proven defaulted to that same zero value, so every unproven message passed authentication. No Merkle proof was required.

What followed was unusual in scale. Once the first successful transaction was visible on chain, anyone could copy its calldata, substitute their own address and withdraw. Nomad counted over 300 unique addresses taking part. The bridge held ETH, USDC, WBTC and assorted ERC-20 tokens.

Published figures differ modestly. Nomad's own accounting and the FTC's later complaint both put the loss at about $186 million; TRM Labs says $190 million; early coverage described it as nearly $200 million. Nomad honoured 10 per cent bounty requests from returners. About $37.5 million came back, roughly 20 per cent of the total, which the FTC's December 2025 order requires be distributed to affected customers.

The FTC found Nomad had been warned internally about inadequate testing and deployed the code anyway, and that consumer losses were approximately $100 million. According to the FTC's complaint as reported, the security firm Quantstamp flagged the vulnerability in a June 2022 audit and the Nomad team concluded the auditor had misunderstood the issue. Quantstamp has separately disputed the extent to which the deployed code matched what it reviewed; that dispute is not resolved here.