An attacker exploited predictable wallet seeds generated with insufficient randomness in Qubic’s wallet software, compromising 1,404 user wallets and stealing approximately 2.94 trillion QU. The vulnerability affected certain wallets created on Apple devices and Safari browsers. Qubic halted its network at tick 85,371,949, while MEXC froze the account receiving the remaining stolen funds. Seed generation was corrected in wallet version 4.26.4

An attacker exploited insufficient randomness in some Qubic wallet seed generation (affecting seeds created in any browser on iPhone/iPad, Safari on Mac before Oct 18, 2026, or the Qubic iOS app before July 2025), draining approximately 2.94 trillion QU (~$1.3 million) from 1,404 wallets. The issue was in seed generation, not the Qubic protocol. The network was halted, most funds frozen, and seed generation fixed in version 4.26.4.