Zano has taken the extraordinary step of restarting its blockchain from a block produced roughly one month ago after discovering a vulnerability in its recently introduced Gateway Address system that allowed unauthorized ZANO and fUSD to enter circulation.
Under the recovery plan, the network has been restarted from block 3,833,000, immediately before Hard Fork 6 activated on August 26. That means transactions confirmed after that point are not part of the recovered blockchain, even when those transactions had nothing to do with the vulnerability.
In Zano’s recovery announcement, the core team said its investigation found no compromise of wallet spend keys, ordinary transaction privacy or Zano’s underlying consensus mechanism. The problem instead involved Gateway Addresses and their interaction with asset issuance, including the network’s fUSD stablecoin.
Zano has not yet disclosed how much unauthorized ZANO or fUSD entered circulation, who exploited the vulnerability or the precise technical mechanism that made the issuance possible. The team said a full technical explanation will follow, including a review of related Gateway Address code.
The Recovery Removes More Than the Unauthorized Coins
The rollback solves one problem cleanly on Zano itself: activity occurring after block 3,833,000 disappears from the recovered version of the ledger. But it also removes roughly a month of legitimate chain history.
Users who sent normal payments during that period may therefore find that transactions they previously considered final no longer exist on the recovered chain. Zano is telling users to preserve transaction IDs and trade records, update their wallets and verify the final status of transactions before attempting to resend anything.
The process also depends on much more than ordinary wallet users updating software. Miners, stakers, full-node operators, exchanges, bridges, payment providers and third-party wallets must each migrate to the recovered chain.
That introduces the possibility of temporary infrastructure fragmentation. A user operating on the recovered network could send funds to a service still following the abandoned chain. Zano has consequently warned users to confirm that exchanges and other services have completed the migration before transferring assets.
The problem resembles the broader operational risks that appear when blockchain infrastructure changes underneath existing balances. A recent Sei stablecoin migration, for example, showed how assets can remain visible while the infrastructure needed to move or convert them changes around users.
Off-Chain Trades Cannot Be Rolled Back With the Blockchain
The most difficult part of Zano’s recovery begins where the Zano blockchain ends.
The team explicitly acknowledged that restarting its ledger cannot reverse payments already settled in USDT, DAI or other assets on separate networks. That distinction potentially matters for exchanges, swap providers and bridges that accepted ZANO or fUSD and delivered another asset in return during the affected period.
Suppose an exchange credited a ZANO deposit during September, allowed the customer to sell those coins for USDT and subsequently allowed that USDT to be withdrawn. Removing the original ZANO transaction from the recovered blockchain does not bring the withdrawn USDT back. The exchange is left with an accounting discrepancy that exists outside Zano’s restored ledger.
A similar problem can arise with bridge transactions or swaps. Once value crosses into another network, restoring the source blockchain cannot automatically reconstruct the economic state that existed before the transfer.
That is why recovery is likely to require transaction-by-transaction reconciliation rather than simply installing a software update. Zano says it is working with affected projects and counterparties and intends to publish a reimbursement and claims process. The team has said it wants affected users and businesses to be made whole, but it has not yet published the amount involved or detailed compensation rules.
The distinction between what a protocol can reverse and what external counterparties have already settled is also visible in other security incidents. After the recent Bitget breach, for example, stolen XRP moving beyond immediately controllable accounts illustrated how recovery options narrow once assets move into infrastructure governed by different rules.
The Feature Built for Exchanges Is Now Creating an Exchange Reconciliation Problem
The irony is that Gateway Addresses were designed specifically to solve Zano’s integration problem.
Zano is a privacy-focused blockchain whose ordinary wallet architecture historically created additional engineering requirements for exchanges and cross-chain platforms. Gateway Addresses introduced an account-style address with a directly trackable balance, giving outside services a simpler interface for deposits, withdrawals and balance monitoring.
Before Hard Fork 6, Zano described the feature as infrastructure intended for exchanges, bridges and decentralized exchanges. The project said it could reduce the engineering burden that had prevented some services from integrating the privacy chain.
Hard Fork 6 activated at block 3,833,000 on August 26 after more than a year of development. Zano said at the time that Gateway Addresses would support easier exchange integration, payment IDs and cross-chain infrastructure while leaving ordinary private wallet activity unchanged.
One month later, the same integration layer has forced the network to return to the exact point immediately before it existed.
That does not establish that Zano’s underlying privacy technology or consensus failed; the project specifically says they did not. But it does make the Gateway Address implementation itself a much more important piece of infrastructure than its apparently narrow purpose might suggest.
Accounting boundaries can become security boundaries. A bug that allows an integration-facing component to create unauthorized economic value can propagate through exchanges, bridges and other systems even when core wallet keys remain secure. Other protocols have faced similar risks when a flaw threatens to desynchronize on-chain and application accounting.
The Real Test Is What Happens to Everyone Who Traded During September
For investors, the size of the unauthorized issuance will matter, but it may not be the most important number.
The harder question is how much legitimate economic activity occurred during the abandoned month and how much of it crossed into systems that cannot simply follow Zano’s rollback.
If two users transferred ZANO between their own wallets, reconciliation may be relatively straightforward. An exchange deposit followed by a trade, a bridge transaction, a merchant payment or a conversion into another asset is more complicated because another party may already have delivered irreversible value.
That leaves exchanges in a particularly sensitive position. They will need to determine which deposits exist on the recovered chain, which customer balances were created from transactions that no longer exist, whether those balances were traded, and whether proceeds were withdrawn. Privacy features could make some forms of investigation more complicated than on fully transparent ledgers, although Gateway Addresses themselves were specifically designed to expose service-facing balances.
Zano’s separate warning about a fake wallet distributing remote-access malware adds another layer of operational risk. Users urgently searching for the required emergency software update are unusually attractive phishing targets, meaning transaction discrepancies caused by the chain recovery could become mixed with entirely separate losses caused by malicious software.
The eventual technical report will therefore matter well beyond explaining the original bug. Investors and infrastructure providers will want to know why testing before Hard Fork 6 failed to catch it, whether adjacent Gateway Address functions share the same weakness and what safeguards will prevent another issuance problem after the feature is reintroduced.
The reimbursement framework may be equally revealing. A blockchain rollback can rewrite protocol history, but it cannot rewrite the balance sheets of every exchange, bridge, trader and payment provider that acted on that history while it was considered valid.
Zano has successfully chosen a chain state that eliminates the unauthorized activity. The much harder task now is reconstructing the economic reality that developed during the month it erased.
Johan Shamshad is a financial markets writer at Dave Finances covering cryptocurrencies, trading platforms, brokers, fintech, financial regulation, and developments across global markets. He previously worked at Gulf News, adding newsroom experience to his coverage of fast-moving financial and digital-asset markets.
His work focuses on identifying market-moving events, company developments, regulatory changes, product launches, and shifts in trading and financial infrastructure.
Johan contributes news and analysis designed to help readers understand not only what happened, but why a development matters and how it may affect the wider financial landscape.