Qubic has brought its blockchain back online after an emergency halt triggered by the theft of about 2.94 trillion QU tokens from 1,404 wallets. The stolen amount was valued at nearly $1.3 million, and the network interruption was used to stop further losses and contain the attack.
The project says the breach did not come from a failure of the blockchain itself. According to Qubic, the attacker took advantage of weak recovery-seed generation in older wallet software, allowing access to certain wallets without breaking the network’s core infrastructure.
Network halt and restart
The incident unfolded on Oct. 18, when the theft was carried out in less than two hours. In response, Qubic’s validators, known as Computors, stopped transactions at tick 85,371,949 as an emergency measure.
By the evening of Oct. 19, the blockchain was processing transactions again. Qubic said on Oct. 20 that its validators had approved a recovery plan, opened a claims portal and started sending payments to victims whose claims had been verified.
How the wallets were exposed
Qubic said the weakness was tied to the way some older wallet versions generated recovery seeds, the secret phrases or strings that control access to funds. The issue affected wallets created through browsers on iPhones and iPads, Safari on Macs, and older versions of Qubic’s iOS app.
According to the project, the random-number generator used in those cases was not secure enough for cryptocurrency wallets. That meant attackers could potentially rebuild predictable recovery seeds and enter affected wallets even without the owners’ passwords.
Qubic said the flaw was fixed in wallet version 4.26.4, released around Oct. 19, by replacing the older generator with a more secure method. The team also warned that updating the app does not make an old seed safe again, meaning users who created wallets with affected software need to create entirely new wallets and move their funds.
Where the stolen tokens are now
Qubic said most of the stolen cryptocurrency did not leave reach after the shutdown. About 87.1% of the stolen QU remained stuck onchain, while an exchange froze an account holding the remaining 12.9%.
The project said it has moved the affected onchain funds into protected escrow so validators can return tokens to verified owners. Any recovery tied to the exchange-held portion, however, depends on the exchange and on any law-enforcement proceedings that may follow.
Claims process and next steps
Victims can submit claims through Qubic’s official recovery portal until May 1, 2027. The project said applicants must provide the identity of the affected wallet, a newly generated destination wallet, a signed ownership message and supporting evidence.
Approved claims are subject to a seven-day dispute period before payment is made. Qubic has also warned users that legitimate recovery help does not require handing over a wallet seed or paying any fee.
The immediate next confirmed step is the ongoing review and payout of verified claims. More broadly, the incident highlights a distinction often seen in crypto security incidents: a blockchain can remain uncompromised while weaknesses in wallet software still expose users to major losses.
Source: news.bitcoin.com