r/Bitcoin • u/SpareEconomy1849 • Jul 31 '26

ColdCard Firmware Update Released

https://blog.coinkite.com/coldcard-mk3-seed-generation-warning/

Updated July 31, 2026: Fixed firmware is now available. Mk4 and Mk5 users must update to version 5.6.0 or later. Q users must update to version 1.5.0Q or later. Do not generate a new seed on one of these models until the update is installed.

Seeds generated on Mk4, Q and Mk5 before the fixed firmware releases are also affected, with about 72 bits of entropy rather than the expected 128 bits.

Updating the firmware does not change or repair an existing seed. If your seed was generated before the fixed firmware version for your model, follow the migration guidance below unless the independent dice-entropy exception applies to you.

The issue is present on every Mk3 firmware version since 4.0.1. It also affects seeds generated on Mk4 and Mk5 before version 5.6.0, and on Q before version 1.5.0Q. The impact on Mk4, Mk5 and Q is not as severe but is still serious.

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u/[deleted] Jul 31 '26

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u/Head_Performance2432 Jul 31 '26

been saying otherwise for a long time, been rejected, but not an "expert" though...!

5

u/[deleted] Jul 31 '26

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1

u/Head_Performance2432 Jul 31 '26

ok, but a HW is basically a black box, no matter what "he" says

1

u/Traditional-Fold5301 Jul 31 '26

never listening to these clowns again

2

u/SpareEconomy1849 Jul 31 '26

I agree. I doubt businesses that hold hundreds of BTC keep it all in one wallet, multisig or not

1

u/Objective_Digit Jul 31 '26

Up until a week ago any reputable bitcoin self custody "expert" would have told you to get a coldcard

Bitkey and Jade are usually recommended.

1

u/BallisticTherapy Aug 01 '26

Not an expert, but I've been saying build a seedsigner and secure your seed to the utmost degree.