Hack history / 2026 / Hack or exploit
Secondfi
Hack or exploit on Jun 23, 2026 · Weak Key Generation
SOURCES AGREE ON DATE AND LOSS · 4 SOURCES
Lost
$2.4M
dollars at the time
Returned
none listed
as the sources state it
Rank
#642
among thefts by dollars lost
What happened
Between June 21-23, 2026, deterministic nonce reuse in SecondFi's Cardano signing code (one missing line) exposed 374 wallet private keys through all historical signatures. Attacker drained 16.1M ADA (~$2.4M); white hat protected $18.5M ADA. Total exposure: $20M+.
Details
- Date
- Jun 23, 2026
- Kind
- Hack or exploit
- Method
- Weak Key Generation
- How in
- Keys, accounts and infrastructure
- Target
- Wallet
- Chains
- Cardano
Related incidents
Cite this page
SwanBluechip, "Secondfi hack, Jun 23, 2026: $2.4M lost", Crypto hack history, https://swan-hack-tracker.pages.dev/history/i/ht38168befb0/ (data as of 2026-10-31).