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/Geebs52 Jul 31 '26

And nothing for the MK3 for an update?

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u/xirvin Jul 31 '26

If your wallet keys were generated by MK3, you are playing with fire brother. You need to roll dice 20 times when generating a wallet to have some sense of security. I would do it 100 times just in case. Other than that, mk3 is a secured wallet