Qubic halts network after 1,404 wallets drained via weak iOS seeds

Qubic (QUBIC) validators halted the layer-1 at tick 85,371,949 on October 18 after an attacker drained 1,404 wallets between 23:42 UTC Saturday and 01:26 UTC Sunday, lifting approximately 2.94 trillion QU (about $1.3M at the pre-event price). Per Qubic's own post-mortem, the attack did not touch the protocol — it exploited predictable 55-character wallet seeds generated by older Qubic software on Apple devices.

The incident is written up by Bitcoin.com News and in French by Cryptoast, both citing the Qubic team's statement on X.

What happened

Qubic's wallet code was generating seeds with insufficient randomness in the following configurations:

• iPhone or iPad in any browser, before October 18, 2026
• Mac running Safari, before October 18, 2026
• Qubic iOS app, before July 2025

An attacker enumerated weak-seed candidates and systematically swept the matching addresses during a two-hour window overnight. The sweep did not require any protocol-level flaw — the seeds themselves were derivable.

Validators (Qubic calls them Computors) triggered a preventive network halt at tick 85,371,949, freezing in-flight transactions. Of the stolen QU, Qubic reports:

• 87.1% remained on the Qubic chain and is frozen by the halt.
• 12.9% was moved to a MEXC deposit address before the halt; MEXC froze the receiving account within about an hour of being alerted, per the Bitcoin.com piece.

Bitget suspended QUBIC deposits and withdrawals for maintenance. QEARN stakes were reportedly unaffected. The native token was down more than 10% at 10:00 ET Sunday.

Numbers

• Wallets drained: 1,404
• QU stolen: ~2,940,000,000,000
• USD value: ~$1.3 million (at pre-event QU price near $0.0000005)
• Frozen on-chain: 87.1% (~$1.13M)
• Routed to MEXC and frozen there: 12.9% (~$168k)
• Patch version: v4.26.4

Attribution

No actor has been named. On-chain history of the receiving addresses before the sweep has not been published by Qubic or by the exchanges. Treat any "the attacker is X" claim circulating on X without a chain-of-custody trace as unverified.

What to watch

1. The Computor-quorum restitution vote. Qubic says victims who register their wallet ID, loss amount and transaction link on the Qubic explorer may be eligible for a resolution decided by Computor consensus. The specifics — pro-rata reimbursement from the frozen 87.1%, a protocol inflation, or none — are not fixed yet. A community poll is open on Discord.
2. MEXC's handling of the 12.9%. The exchange has frozen the receiving account but has not published whether the funds will be returned to Qubic or held pending court action. MEXC's recent track record on frozen funds (see the February 2026 ZachXBT thread and multiple user complaints about multi-million-dollar freezes) is uneven.
3. An audit of Qubic's seed generation. Qubic ships v4.26.4 as the fix. A third-party cryptographic review is not yet announced — but it should be. The underlying question is whether the entropy source was Math.random(), a short PRNG state, or a timing-biased WebCrypto call. The answer determines whether earlier seeds generated on any platform remain exposed.

Context

This is Qubic's second security incident in three months. In July 2026 a compromised account accessed the Qubic GitHub organization and extracted sensitive material from the code repository; web-wallet users who unlocked wallets during a specific UTC window were advised to migrate identities. ChainCatcher covered the July incident at the time.

Weak-randomness bugs are not a Qubic-specific class. The pattern is familiar from the 2023 Libbitcoin "Milk Sad" seed flaw and the 2026 Coldcard firmware issue that let attackers sweep more than 5,200 Bitcoin addresses. The common root cause is the same each time: entropy supplied by a general-purpose scripting runtime rather than by a dedicated CSPRNG. Mobile Safari's historical WebKit random-number generator (CVE-2010-3804 and successors) is a particularly well-known offender.