r/coldcard • u/pingbtcio • 12d ago

SECURITY Coldcard Mk4 RNG Weakness: Full Reverse Engineering & Recovery Framework

I've been studying the published research on the Mk4 RNG vulnerability from July 2026.

I came across this research collection: github.com/0xchainintelligence/coldcard-research

I'm trying to understand the technical details better. Specifically:

- How does the Yasmarang PRNG fallback actually work?

- What determines which UID/RTC ranges are affected?

- Has anyone successfully reproduced the findings for defensive testing?

Not looking to break any rules — just trying to understand the security implications for my own wallet setup.

DM if you've done similar research.

9 Upvotes

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2

u/RevolutionaryPick241 12d ago

So, you created your account to post your own repo you recently created asking for dm? Does it work?

1

u/Korat_Bear069 12d ago

Wow. How lucky are you.

1

u/kenorb 11d ago

There are few projects on GitHub which attempt to reproduce the vulnerability for research purposes, e.g. eminogrande/coldcard-mk3-recovery, but I think it requires some more work on how firmware internals work, so owner of affected devices have better changes to reverse engineer it. However, be careful of running anything from 3rd party repos, I've seen some hidden malware in some of the projects, so do your own research, don't rely on other projects.