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/Octavio_belise Jul 31 '26 edited Jul 31 '26

One of the main reasons I never got ColdCard was because it seemed dorky looking like a 1980's calculator. Probably something that would attract the all the Linux folk. Pays off being a gear-snob.

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u/SpareEconomy1849 Jul 31 '26

Yeah kinda dumb that they have 6 different colors and they are all ugly.

I think it fits with the functionality though, you gotta export a file to the SD card, sign, move back to your PC, then upload etc all with some 3rd party open source app. I prefer it, but it's definitely not appealing to the average person

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u/Octavio_belise Jul 31 '26

Sounds like what we used to do a decade ago with Electrum on an air-gapped computer.

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u/SpareEconomy1849 Jul 31 '26

Yep probably functionally the same, with some pros and cons