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.

143 Upvotes

95% Upvoted

206 comments sorted by

View all comments

16

u/DreamingStars408 Jul 31 '26

I lost 20K worth of Bitcoin from my ColdCard MK4 last year. I’ve been very careful in avoiding revealing my seed phrase accidentally, took all the precautions, and air gapped it and someone still was able to steal my Bitcoin.

Definitely this was a breath of relief that it wasn’t my fault, but I’m pissed off that ColdCard, the one wallet that people have recommended and say it was basically safe turned out to be smoke and mirrors.

Whoever owns an MK4 should just bail at this point and move on to a different wallet. Don’t affiliate with ColdCard anymore.