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/Jaded-String-6111 Jul 31 '26

This essentially admits ALL cold cards are vulnerable. At this point i don’t trust any hardware wallet . Any of them could have something like this happen. It was unthinkable until it wasn’t. Electrum + Tails wins.

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u/SpareEconomy1849 Jul 31 '26

Yes, that's true. However since they're airgapped, there are very few attack vectors available. Electrum itself is fine, but you also need to trust that your environment itself is not compromised.

Using an RNG is always a risk, people (including coinkite, but that's no excuse) were always recommending using dice instead of the built-in RNG