Last updated: August 1, 2026
At the end of July 2026, bitcoin was stolen due to a flaw in the Coldcard firmware. This page explains in Dutch what happened, whether you’re at risk, and what you can do about it, calmly, without panicking, and without having to study cryptography first.
If you purchased your Coldcard from us, you’ve already received a personal message about this. If you bought it somewhere else, this explanation applies to you just as well, and you’re welcome to email us if you get stuck.
Read this first
We will never ask you for your 24 words. No one does. Not by email, not over the phone, and not via a website that offers to check if you are vulnerable. Such sites exist now, and they are there to rob you.
There are currently many scams circulating related to this topic. Only download firmware from coldcard.com, and go there by typing the address directly into your browser. Do not use a link in an email, not even a link in an email from us.
What happened
In March 2021, a design flaw crept into an update to the Coldcard firmware. As a result, when generating a seed, the device did not use the hardware random number generator, but rather a predictable software alternative. This went unnoticed for five years.
On July 30, 2026, this vulnerability was exploited. In less than half an hour, approximately 594 bitcoin were stolen from about 500 wallets. Coinkite, the developer of Coldcard, confirmed the vulnerability and immediately released a patch.
Which models are affected
| Model | Strength of the key | Situation |
|---|---|---|
| Mk3 | about 40 bits | Serious. This is where the theft happened. |
| Mk4, Mk5, Q | approximately 72 bits | Weaker than intended, but practically uncrackable. No known thefts. |
128 bits was intended. The Q, Mk4, and Mk5 score higher because those models mix in extra randomness from two security chips. That difference is precisely the reason why nothing was compromised in those models.
The recovery firmware:
- Coldcard Q: version 1.5.0Q or newer (Edge: 6.6.0QX)
- Mk4 and Mk5: version 5.6.0 or newer (Edge: 6.6.0X)
- Mk3: version 4.2.0
Are you at risk
You are not affected if one of these points applies to you:
- You have imported your seed. Whoever entered their 24 words themselves, from paper or another device, is not affected. The error only lies in the creation.
- You have worked with dice. At least 50 fair, privately rolled throws during the seed creation. That randomness came from you and has not been compromised. If you want certainty, aim for 100 throws.
- You use a strong, unique passphrase. That is a completely separate wallet. Highly protective, but it remains a band-aid on a weak foundation, so migrating remains the advice.
Are you not sure? Then assume you have been hit. That is also Coinkite's stance.
What you need to do
First things first: Take your time. This month, not tonight. Rushing to move your bitcoin right now poses a greater risk than the error itself. Most people who lose money because of this lose it due to an error in their own backup, not because of an attacker.
Step 1. Update your Coldcard
Download the firmware from coldcard.com by typing in the address yourself. For the Q, you'll need version 1.5.0Q or newer.
Step 2. Create a new seed
This is the step people skip. Just updating does not repair your existing seed, it stays exactly as it was. A new one really has to be created.
On updated firmware, the device's own randomness is sufficient again. Dice are optional. If you still want to use them, do at least 50 rolls, and do all of them.
Step 3. Check your backup before sending anything
Write down the new words and verify them on the device. Never store them digitally: no photo, no password manager, no cloud, do not type them on a computer.
Step 4. Test with a small amount
Send something small to your new wallet and retrieve it again. If that works, your backup is correct and your setup is correct.
Step 5. Move the rest, in steps
And keep your old backup until everything has arrived and been confirmed. Do not throw it away as soon as the first transaction has been sent.
Over passphrases
If you use or are going to use a passphrase: choose six random words yourself. Never let an AI generate or check your passphrase. That's not just theoretical advice; it's exactly the kind of mistake that causes people to lose their bitcoin.
Please also note: your passphrase is not verified in any way. Any passphrase will open a valid wallet, even one with a typo. The only difference is that your bitcoin won't be in it. Therefore, always check the fingerprint.
What we learned from this
Two things, and we apply both of them.
First of all, adding your own randomness is not paranoia. Anyone who used dice at the time was not affected by this error. That advice is now standard in our manuals and in the box.
Secondly, trusting a single vendor is a risk you bring upon yourself. A passphrase or a multisig setup ensures that a mistake by a manufacturer doesn't cost you your entire stack.
Need help
Are you stuck, or does this just seem a little daunting? Email us. We'll walk you through it step by step, even if you didn't buy your Coldcard from us.