⚠️ Coldcard Security Incident: What Happened, Who Is at Risk, and How to Protect Your Bitcoin

The Bitcoin community has just witnessed one of the most significant hardware wallet security incidents in recent years.

Roughly 594 BTC, worth tens of millions of dollars, were reportedly stolen from hundreds of wallets in a coordinated attack. This wasn't caused by malware on users' computers or phishing emails. Instead, the problem appears to be linked to the way some Coldcard devices generated their seed phrases.

Let's break down what happened and, more importantly, what users should do next.

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What is the issue?

Every Bitcoin wallet starts with a seed phrase.

That seed must be created using high-quality randomness (entropy). If the randomness is weak or predictable, an attacker can theoretically regenerate the same seed and therefore steal the Bitcoin protected by it.

Current investigations indicate that certain Coldcard firmware versions did not use as much unpredictable entropy as intended during seed generation. Instead of producing a fully random seed, the generated keys could become significantly more predictable under specific conditions.

This appears to be exactly what attackers exploited.

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Which devices are affected?

The highest risk currently applies to:

• Coldcard Mk3
• Seeds generated on vulnerable firmware versions
• Wallets created without additional dice entropy
• Wallets that did not use a BIP39 passphrase

Later models (Mk4, Mk5 and Q) are considered much safer, but Coinkite has still released updated firmware and recommends users migrate away from seeds generated before the fixes unless they independently supplied sufficient entropy (for example by using dice rolls).

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Why firmware updates alone are NOT enough

Many people believe that updating firmware fixes everything.

Unfortunately, that is not true.

If your seed was originally created using weak entropy, updating the firmware does not magically create a new secure seed.

Your wallet will continue using the old private keys.

The only permanent solution is to:

• generate an entirely new seed,
• verify that it is safely backed up,
• and move your Bitcoin to the newly created wallet.

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What should affected users do immediately?

If you believe your wallet may be affected:

1. Stop using the old wallet for long-term storage.

2. Update your device to the latest firmware.

3. Create a completely new wallet using the updated firmware.

4. Prefer adding your own entropy (dice rolls) if your hardware wallet supports it.

5. Move every satoshi from the old wallet to the new one.

6. Double-check your backups before transferring larger amounts.

Never rush.

Always send a small test transaction first.

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Extra protection: Passphrases and Multisig

This incident also reminds us why many advanced Bitcoin users prefer additional security layers.

BIP39 Passphrase

A passphrase creates an entirely separate wallet from the same seed.

Even if someone discovers your seed phrase, they still cannot access your Bitcoin without the correct passphrase.

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Multisig

Instead of trusting a single hardware wallet, many Bitcoiners use a 2-of-3 multisignature wallet.

Example:

• Trezor
• BitBox02
• Foundation Passport

or

• Trezor
• BitBox02
• Specter DIY

Now an attacker would need to compromise multiple independent devices before your Bitcoin could be spent.

No single hardware manufacturer becomes a single point of failure.

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Lessons for every Bitcoiner

This incident is not proof that hardware wallets are unsafe.

Quite the opposite.

It reminds us that security is a process, not a product.

No manufacturer is perfect.

Open-source software, independent audits and quick disclosure are exactly why problems like this eventually become visible.

The important part is how we respond.

• Verify.
• Update.
• Migrate when necessary.
• Diversify your security.

Bitcoin gives us complete financial sovereignty.

With that freedom comes the responsibility to continually improve how we protect our keys.

Stay humble.

Stay sovereign.

Stay safe.

^{Vote for the BBH Witness}

^{[email protected]}


Images and screenshots are from me or AI generated