What the developer wrote
Authored by Peter D. Gray
cautions
What changed, and why it matters
This commit adds a security advisory to the COLDCARD firmware README. Coinkite states that firmware releases from 2021 through July 2026 contained a bug that produced weak randomness (poor entropy) when generating secrets such as wallet seed phrases. Because weak randomness can make private keys guessable by attackers, any Bitcoin or other cryptocurrency funds protected by seeds created on affected COLDCARD devices during that period may be at risk of theft. The advisory recommends regenerating seeds and moving funds immediately, and lists specific firmware versions where the issue is fixed. The commit itself only changes documentation; it does not contain the actual code fix.
Users with COLDCARD devices should verify whether their firmware version is within the affected range (2021 through July 2026, below the listed fixed releases). If affected, they should upgrade to a fixed firmware version, generate a new master seed in a known-safe manner (preferably with strong additional entropy such as a high-entropy BIP-39 passphrase and/or dice rolls), and move all funds from addresses derived from the old seed to addresses derived from the new seed as soon as possible. Review the linked Coinkite blog posts for detailed guidance and any further updates.
Security signals we found
Vendor self-disclosed security advisory in project README
Weak/poor entropy in cryptographic secret generation
Affected period spans multiple years (2021 to July 2026)
Recommendation to rotate secrets and move funds immediately
Fixed firmware versions explicitly listed
Documentation-only commit; actual patch is elsewhere
Evidence from the diff
The commit (266f581a24b914285e249b91c997b578ddf277e8) is a documentation-only change to README.md that inserts a ‘Security Advisory’ block. According to the added text, COLDCARD firmware versions spanning 2021 to July 2026 generated secrets with insufficient entropy, meaning master seeds and derived private keys may be predictable or brute-forceable. The advisory identifies fixed release boundaries: 5.6.0 for Mk4/Mk5, 1.5.0Q for Q1, 4.2.0 for Mk3, and 6.6.0 for Edge Mk/Q. It notes that BIP-39 passphrases can mitigate risk depending on user-supplied entropy, and that dice rolls contribute approximately 2.5 bits per roll. Two Coinkite blog posts are linked for further details. The diff does not show the underlying entropy bug or its code fix; it only records the public disclosure and remediation guidance.
Changed components
COLDCARD firmware seed/private key generation (all models: Mk3, Mk4, Mk5, Q1, Edge Mk/Q)README.md documentationInspect captured patch +18 / −0
diff --git a/README.md b/README.md
index 6029f5d..f14c74a 100644
--- a/README.md
+++ b/README.md
@@ -1,3 +1,21 @@
+```diff
+## Security Advisory
+
+- Versions from 2021 to July 2026 had a bug which produced poor entropy.
+- Any secrets generated on a COLDCARD in that period should be regenerated and
+ funds moved on chain **immediately**.
+- Master seeds can only be trusted from releases after these levels:
+ - 5.6.0 (Mk4, MK5)
+ - 1.5.0Q (Q1)
+ - 4.2.0 (Mk3)
+ - 6.6.0 (Edge Mk/Q)
+- Using a BIP-39 passphrase mitigates some of the risk, although it relies
+ on the entropy your passphrase adds. Dice rolls introduced into the secret
+ provide 2.5 bits of entropy per roll.
+- [Blog post and updates](https://blog.coinkite.com/coldcard-mk3-seed-generation-warning/)
+- [Technical background on the bug](https://blog.coinkite.com/entropy-technical-backgrounder/)
+```
+
# COLDCARD Hardware Wallet
Coldcard is an Affordable, Ultra-secure & Verifiable Hardware Wallet for Bitcoin.
Why this scored 100/100
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