Layer-1 blockchain Qubic has restarted its network and launched a recovery process after a wallet-seed vulnerability allowed an attacker to drain roughly $1.4 million in QU tokens from 1,404 accounts, according to the project's latest update.

The network's blockchain explorer shows Qubic resumed processing ticks at 8:00 pm on Oct. 19, advancing beyond tick 85,371,949, where the chain had been halted on Sunday.

Computors approve recovery plan

Qubic said its network validators, known as Computors, approved a recovery plan, and the project has launched a claims platform for affected wallet holders. Affected users can check their address and submit a claim through Qubic's reclaim platform, and have until May 1, 2027, to file, according to the project — a deadline that gives affected holders more than a year to verify eligibility and submit.

The chain was halted on Sunday to prevent any further movement of the stolen funds after attackers exploited predictable wallet seeds generated by vulnerable wallet software.

Predictable seeds from insecure randomness

The flaw affected wallet seeds generated using Qubic's web wallet on certain Apple devices and browsers, where an insecure random-number generator could produce predictable seeds. A wallet seed is the master value from which a user's private keys and addresses are derived; if its generation is predictable, an attacker can reproduce it and unlock funds without ever accessing the victim's device. That is the mechanism behind the mass drain — and why the flaw mattered even for accounts the attacker never touched. Qubic said on Sunday that the seed-generation flaw had been fixed in the latest version of its web wallet.

In an X post on Tuesday, the team said: “If you created your wallet with the Qubic web wallet before version 4.26.4 (released 19 October), treat it as insecure, even if your funds were never touched.”

“Update to web wallet 4.26.4 or later, then create a new wallet,” the team said. “Move your funds to the new wallet as soon as you can, and never use the old one again.”

The guidance extends beyond the 1,404 drained accounts, since any seed produced by the same flawed randomness carries the same underlying weakness.

Background: Qubic's network

Qubic is a layer-1 network founded by Sergey Ivanchlo, a co-founder of IOTA. Its consensus relies on 676 validators known as Computors, who publish “ticks” — the ordered units of ledger progress — roughly every second. The project drew wide attention in 2025 for its useful proof-of-work model, which directs mining power toward training artificial intelligence models.

That fixed validator set is also what made a coordinated response possible: with consensus in the hands of a defined Computor membership, the network could halt at a specific tick, approve a recovery plan, and resume from the same point on the ledger.

Related: Qubic freezes chain after attacker drains 1.4K wallets with weak seeds