Zano has rolled back its blockchain by approximately one month following a vulnerability in Gateway Addresses that permitted unauthorized ZANO and Freedom Dollar (fUSD) tokens to enter circulation, the project's core team announced Sunday.
The Zano blockchain was restarted at block 3,833,000, positioned immediately before Hard Fork 6, which introduced the affected feature. The recovery requires participation from nodes, miners, stakers, exchanges, and other services to adopt the update.
Impact of the Rollback
The rollback invalidates all legitimate transactions conducted during the month-long period alongside the unauthorized tokens, meaning transactions from that timeframe will no longer appear on the recovered chain. The team noted the rollback cannot reverse payments already settled on other blockchains. Zano said it is working to account for losses and will publish a reimbursement and claims process.
Zano's head of marketing and growth Quinten van Welzen stated the rollback was necessary to maintain the blockchain's fundamental property of fixed token supply. "Doing nothing meant unauthorized ZANO and fUSD in circulation without limit, diluting every holder and breaking the most basic promise a currency makes: a fixed supply," van Welzen said.
Gateway Address Feature
Zano has not released a detailed post-mortem analysis at the time of publication, but confirmed the vulnerability originated from Gateway Addresses, a feature designed to simplify integration for bridges, exchanges, and payment services. The feature allows these services to manage funds through a single account-style balance, similar to other blockchains.
Prior to Gateway Addresses, Zano's standard wallets tracked funds as separate transaction outputs (UTXOs) rather than a single account balance. Exchanges and other services previously had to scan the blockchain to identify incoming payments, track those outputs, and select which ones to spend when processing withdrawals.
Background
Zano launched in May 2019 as a layer-1 blockchain focused on private payments. Its standard private transactions conceal senders, receivers, transferred amounts, and asset types. While ZANO is the native token, the blockchain also allows users to deploy and mint custom digital assets, including Freedom Dollar (fUSD).
