SecondFi — Cardano Wallet Nonce-Derivation Key Compromise

Timeline: T0, wave 1 (June 21, 2026, 20:29:41 UTC): Three collector wallets ignite in the same second and begin sweeping long-dormant Cardano wallets (some untouched since 2020) into Minswap V2 and other DEX contracts, draining ~12.3M ADA directly from 198 wallets. T0+2min (20:31:15 UTC): Documented victim drain of 38,421.556 ADA. June 21-22: First public community reports of unauthorized drains begin circulating. T0, wave 2 (before dawn, June 23, 2026): Hub wallet A1 begins sweeping ~2,874 additional wallets one transaction at a time, including whale wallets dormant since 2020. June 23, ~03:35-03:48 UTC: Largest individual sweeps into hub A1 recorded (5.41M, 5.20M, 4.71M ADA, etc.). June 23, 11:29:29 and 11:39:14 UTC: Hub forwards two blocks of 60,000,000 ADA each into dormant vault A2 (total 129,430,001 ADA across 7 transactions, opened with a 1-ADA test transfer). June 23, 10:41:09 UTC: A 'SecondFi WhiteHat Exploiter'-labeled address returns 316.20 ADA + 28.30 NIGHT to one victim. June 23, 12:20 UTC: Last movement of vault A2 — dormant since. June 23, 2026: SecondFi suspends operations. June 24, 2026: SecondFi publishes official update — root cause identified (deterministic nonce derivation flaw), patch rolled out for unaffected wallets, ~129M ADA secured via emergency rescue and routed to a third-party custodian pending external audit, claims process opened at support.secondfi.io. SlowMist founder Cos (Yu Xian) independently estimates total user losses could exceed $20M. Bitquery Research publishes full forensic reconstruction the same day. June 25, 2026: SecondFi publishes further root-cause clarification and reiterates the seed-phrase warning (last documented activity).