Coldcard Seed Security Update: 65 Key Presses, Old Seeds Unfixable

Coinkite has released fixed Coldcard firmware after a Coldcard seed-generation exploit. The update changes how a new Coldcard seed phrase is created by forcing significantly more physical entropy. New requirement for a Coldcard seed: users must add extra randomness—either 65 key presses (at unpredictable times), 50 die rolls, or 128 coin flips. This reduces reliance on potentially faulty internal randomness. Critical limitation: installing the fix does not repair a Coldcard seed created on affected firmware ranges. If you generated a Coldcard seed with vulnerable firmware, you should create a new seed and migrate funds, because cloning/restoring the words keeps the same weakness. A narrow exception is mentioned only when the user followed the affected workflow and recorded at least 50 private, independent fair die rolls (without exposing the sequence). Recommended versions include Coldcard firmware 5.6.1 for Mk4/Mk5 and 1.5.1Q for Coldcard Q. The advisory also highlights that users should verify the firmware’s digital signature before installing and run a small test transfer before moving full balances. The incident reportedly led to severe losses, with law enforcement investigating, but no verified victim count or total loss figure was published.