Zano has restarted its blockchain at block 3,833,000, the height immediately before Hard Fork 6, after a Gateway Address vulnerability allowed unauthorized ZANO and Freedom Dollar (fUSD) to enter circulation, according to the project’s core team.
The team said on Sunday that the recovery requires participating nodes, miners, stakers, exchanges and other services to adopt the update. The rollback reaches back roughly one month in chain history.
Rollback removes unauthorized tokens and valid transactions
The chain reset invalidates legitimate transactions made during that period along with the unauthorized tokens. As a result, transactions recorded during the affected month will no longer appear on the recovered chain.
Zano also said the rollback cannot reverse payments that have already been settled on other blockchains. The team said it is working to account for any losses and will publish a reimbursement and claims process.
Quinten van Welzen, Zano’s head of marketing and growth, said: “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.”
He added: “It would also tell every future attacker that exploited coins get to keep their value. No project survives that.”
Zano says the issue came from Gateway Addresses
Zano had not released a post-mortem at the time of publication, but it confirmed that the issue came from Gateway Addresses. The feature was built to make it easier for bridges, exchanges and payment services to integrate with Zano by letting them manage funds through a single account-style balance, similar to designs used on other blockchains.
Before Gateway Addresses, ordinary Zano wallets tracked funds as separate transaction outputs, or UTXOs, rather than as one account balance. Exchanges and other services had to scan the blockchain to identify incoming payments, track those outputs and choose which ones to spend when processing withdrawals.
Zano’s blockchain explorer showed the rollback taking place on Sunday.
Network background and token details
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.
Alongside its native token ZANO, the network also allows users to deploy and mint custom digital assets. Freedom Dollar, or fUSD, is one such token operating on the Zano blockchain.
Van Welzen said: “Restarting the chain from before Hard Fork 6 costs a month of history, and it costs trust, which we’ll have to earn back.”
He also said: “But it restores the supply everyone signed up for, and it leaves a path to rebuild. Which is better than 7 years of hard work left to die. We know it hurts. But not doing it would have hurt more.”