On 30 July 2026, Coinkite published a security advisory for COLDCARD hardware wallets. A firmware bug meant that seed words generated on affected devices were far less random than intended, which makes those seeds easier for an attacker to find.
If you have ever created a wallet seed on a COLDCARD, please read this article and check whether you are affected.
What happened
In March 2021, a change to COLDCARD firmware caused wallet seed generation to draw its randomness from a software fallback generator instead of the device's hardware random number generator. Seeds created on affected firmware have far less randomness than the intended 128 bits. Coinkite's preliminary estimate is roughly 40 bits on Mk2 and Mk3, and roughly 72 bits on Mk4, Mk5 and Q.
A seed with that little randomness can realistically be searched for and found. Coinkite has stated that for affected wallets this is a direct security risk, not a theoretical one.
Which devices and firmware are affected
| Model | Affected firmware | Fixed firmware |
|---|---|---|
| Mk2 and Mk3 | 4.0.1 to 4.1.9 | 4.2.0 or later |
| Mk4 and Mk5 (Standard) | Anything before 5.6.0 | 5.6.0 or later |
| Q (Standard) | Anything before 1.5.0Q | 1.5.0Q or later |
| Mk4 and Mk5 (Edge) | Anything before 6.6.0X | 6.6.0X or later |
| Q (Edge) | Anything before 6.6.0QX | 6.6.0QX or later |
Standard and Edge are separate release tracks. If you run Edge firmware, install the fixed Edge release for your model. Do not assume that an older Edge 6.x release is safe simply because its version number is higher than the Standard release.
TAPSIGNER, OPENDIME and SATSCARD are not affected, because they run different code.
Two exceptions
You added 50 or more dice rolls when you created the seed. The bug affected the randomness the device produced by itself. It did not remove randomness that you supplied. If you used Add Dice Rolls when you created your seed and entered at least 50 fair, independent and private rolls, Coinkite does not consider the resulting seed at risk from this issue alone. If you entered fewer than 50 rolls, cannot remember how many you entered, or the rolls were written down, photographed or seen by anyone else, treat the seed as affected.
You use a strong BIP-39 passphrase. A strong, unique and secret BIP-39 passphrase is a separate barrier, because an attacker would have to guess the passphrase as well as the seed. This means a BIP-39 passphrase, not your COLDCARD PIN. A short, common, patterned, quoted or reused passphrase does not qualify, and neither does one you are unsure about. A passphrase reduces your immediate exposure but it does not repair the seed, so Coinkite still recommends replacing the seed as soon as practical.
What to do
- Install the fixed firmware for your model and release track. Download it only from coldcard.com.
- Generate a completely new seed on the updated device.
- Record and verify the new backup, the wallet fingerprint (XFP) and a receive address.
- Send a small test transaction to the new wallet and confirm that it arrives.
- Move the rest of your bitcoin to the new wallet.
- Keep the old backup until the full balance has arrived and confirmed.
Coinkite's advisory has step by step instructions, including a procedure for people whose Mk2 or Mk3 is their only device.
If you have verified a Coldcard wallet with Bitaroo
A new seed is a new wallet, with new addresses and a new extended public key. Anything you previously verified or saved with Bitaroo points at your old wallet.
After you migrate:
- Verify your new wallet or address the next time you withdraw. See Why do I need to verify my wallet or address?
- Remove or replace any saved or whitelisted withdrawal addresses that belong to the old wallet.
Bitaroo Vault, Guardian and the Bitaroo Wallet
None of these products use COLDCARD-generated keys, so none of them are affected by this issue.
- Bitaroo Vault
- Bitaroo Guardian
- The Bitaroo Wallet, which creates your recovery phrase on your own device using the cryptographic random number generator built into your phone. There is no fallback source: if that generator is not available, creating the wallet fails rather than quietly using something weaker.
Guardian is worth one extra note. More than one key is needed to spend from a Guardian wallet, so if one of your own keys was created on an affected COLDCARD, that key by itself does not put your bitcoin at risk. If you created more than one of your own Guardian keys on an affected COLDCARD, or you are not sure which device you used, contact support and we will help you work through it.
Watch out for scams
Security advisories attract scammers. Expect fake emails, text messages, social media accounts and search advertisements offering to check, protect or rescue your wallet.
- Bitaroo will never ask you for your seed words, your BIP-39 passphrase or your private keys. Neither will Coinkite.
- Never type your seed words into a website, an application, or any device other than your hardware wallet.
- Download firmware only from coldcard.com. Do not follow a link from an email, a message or an advertisement.
- Bitaroo will never ask you to move your bitcoin to a safe address.
Where to read more
Need help?
Our team cannot see or access your hardware wallet, and we cannot tell you which device or firmware created your seed. We can help with anything on the Bitaroo side, including verifying your new wallet. Contact support.
This article reflects Coinkite's advisory as at 1 August 2026. Coinkite has said that its investigation is continuing and that a formal technical review will follow, so please check the advisory itself for the latest position.
