Zano restarted its blockchain after a vulnerability in its Gateway Address allowed unauthorized issuance of ZANO and fUSD tokens into circulation, the project said in an announcement on September 27. The network rolled back to block 3,833,000, erasing approximately one month of transaction history to contain the breach.
The vulnerability permitted token creation outside normal minting controls, a class of exploit that can undermine confidence in a protocol's financial integrity and token scarcity. Zano's decision to fork the chain backwards rather than forward places the burden of loss on users and protocols holding positions created after the rollback point; no previous restart of this kind had the consent of all affected holders.
Zano said it is working with affected projects and counterparties to quantify losses and will publish a reimbursement and claims process, though it did not disclose the total volume of unauthorized tokens that entered circulation or name the specific protocols harmed. The project has not yet released the process by which claims will be evaluated or funded.
Chain rollbacks remain rare in production protocols. Ethereum Classic rejected a fork after its 2016 split specifically to avoid erasing history; most protocols treat finality as sacred and absorb losses instead. Bitcoin Cash and other chains have similarly resisted retroactive reversions even after large exploits. Zano's decision to restart from a prior block state deviates from this consensus.
The Gateway Address vulnerability appears localized to one component rather than systemic to the protocol's consensus layer, based on Zano's decision to resume operation without broader architectural changes. The project has not disclosed whether the address was part of a bridge, sidechain connector, or token issuance module.
Zano is a privacy-focused blockchain launched in 2018 as a fork of CryptoNote. Its previous public profile has been modest relative to established Layer 1 networks, with limited liquidity on major exchanges and trading volume below $500,000 per day in recent months.
