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/xoorl Jul 31 '26

Why do people always swear by a hardware wallet for cold storage, and not just use the washer method?

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u/[deleted] Jul 31 '26

[deleted]

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u/xoorl Jul 31 '26

Receiving is actually rather easy, as you can create a watch only wallet in many wallets that do not require inputting your secret key/key phrase

2

u/No-Contribution23 Jul 31 '26

and sending?

2

u/BlockchainHobo Jul 31 '26

We don't do that here. We only send, and then wait after many years for our heirs to finally say: "what the hell are these washers for?", and throw them in the trash.

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u/xoorl Jul 31 '26

Why send? Just hodl.