Urgent wallet safety guide
COLDCARD Vulnerability 2026: Check Your Seed, Not Just Your Firmware
Updating your firmware will ensure new seeds are generated securely, but it cannot make an existing weak seed any stronger. If your current seed was created on affected COLDCARD firmware, follow the steps below and migrate with care.
Read this before making any changes
Updating your device does not fix your current wallet
The firmware fix alters how future seeds are generated. It does not change the words, private keys, or addresses from an existing affected seed. Unless the official independent-dice exception clearly applies, create a new seed and move your funds to it.
Contents
Models and firmware versions affected
Compare the firmware that generated your seed
The firmware version you have now is only part of the answer. You need to know the model, release track, and the firmware that was running when your current seed was first created.
| Model and firmware track | Seed generation affected | Minimum fixed version for new seeds |
|---|---|---|
| Mk2 / Mk3 | Seeds generated on firmware 4.0.1 to 4.1.9 | 4.2.0+ |
| Mk4 / Mk5 standard | Seeds made before the fixed standard release | 5.6.0+ |
| Q standard | Seeds made before the fixed standard release | 1.5.0Q+ |
| Mk4 / Mk5 Edge | Seeds made before the fixed Edge release | 6.6.0X+ |
| Q Edge | Seeds made before the fixed Edge release | 6.6.0QX+ |
Standard and Edge are separate firmware tracks
An older Edge 6.x version isn’t automatically safe just because its number is higher than a standard 5.x. Always check both the model and the firmware track.
Some Coinkite products use different code
Coinkite confirms that TAPSIGNER, OPENDIME, and SATSCARD are unaffected by this seed-generation flaw as they use separate codebases.
Check your device
How to check your installed firmware
According to current COLDCARD documentation, unlock your device, go to Advanced/Tools, Upgrade Firmware, then Show Version. Compare the model, track, and version shown with the latest security status page.
View the official current security statusThe question the menu can’t answer
Which firmware originally generated this seed?Use your setup date, purchase date, firmware history, or your own records to narrow it down. If your seed might have been created on an affected release and you can’t prove otherwise, follow the conservative migration advice.
Simple decision path
Do you need to migrate?
- 01
Was your current seed generated on a COLDCARD?
If not, this particular COLDCARD seed-generation flaw didn’t create it. If yes or you’re unsure, continue.
- 02
Was it created on an affected model and firmware version?
Match the original setup period with the affected firmware matrix. The firmware you have now doesn’t answer this question.
- 03
Did you add at least 50 fair, independent, private dice rolls when creating the original seed?
Coinkite states that a seed meeting all those criteria is not at risk from this RNG issue alone. If you had fewer rolls, exposed rolls, or any uncertainty, you should still migrate.
- 04
Did you use a strong, unique BIP-39 passphrase?
It may slow down an attacker, but it doesn’t fix the weak seed. Unless the dice exception applies, plan a careful migration as soon as possible.
A strong, unique BIP-39 passphrase adds an extra layer of protection and may reduce immediate risk. However, it does not fix the weak seed itself. Coinkite recommends that passphrase users migrate as soon as possible unless the independent-dice exception applies.
What went wrong
Strong cryptography was given weak starting material
Neither Bitcoin nor ECDSA was compromised. The real issue was earlier: some wallet seeds were generated from a much smaller pool of possibilities than users expected.
Expected process path
The dedicated hardware random generator should supply the unpredictable input for seed creation.
Affected process path
rng_get()→ngu.random.bytes()→Wallet seedA build and linking error caused the seed-generation process to use MicroPython’s general-purpose software generator, rather than the intended hardware-based method.
The engineering lesson
Source code may include the correct security component, but the final build could still link to the wrong one.Open source, peer reviews, and reproducible builds help with verification, but they don’t replace full end-to-end testing of the actual call path and linked binary. The fix now includes checks to prevent the wrong RNG symbol being used during the build.
Why these numbers matter
128 bits, 72 bits, and 40 bits are worlds apart
Every missing bit halves the number of possibilities an attacker must try. Losing dozens of bits turns an almost impossible search into a real security threat.
The intended minimum security level for the generated seed.
Extra secure-element input improved things, but the outcome was still well below the intended standard.
A much smaller pool of possible seeds, creating an immediate risk for wallets holding funds.
These are security estimates from the published incident analysis, not a guarantee that every device or seed has the same search space. The practical advice remains: treat any potentially affected seed with caution.
A genuine incident, not just a theoretical risk
Reported thefts brought the flaw to light
Bitcoin Optech estimated that losses had already exceeded 1,000 BTC by 31 July 2026. By 4 August, Galaxy Research had linked 1,596 BTC to three confirmed attack waves. It said a possible fourth wave could take the total to 2,055 BTC, but there was not yet enough confirmation from victims.
TRM Labs published a separate estimate of about 1,816 BTC on 5 August and described it as preliminary. The figures differ because analysts group addresses differently and apply different standards for victim confirmation. They are credible estimates, not a final proven total.
-
The faulty process enters seed generation
The libNgU migration altered the process used to generate wallet seeds.
-
The first public warning emerges
The initial advisory focused on Mk3 and at first considered newer models to be outside the main risk area.
-
The affected scope widens
Guidance was updated to cover Mk4, Mk5, Q, and the separate Edge tracks; fixed releases have been issued.
-
Discussion of losses and technical causes
Coinkite admitted real losses and published further details about the build, linker, and submodule boundaries.
-
Current status and migration information are now combined
Coinkite released a clearer matrix of fixed versions, targeted validation evidence, and a dedicated migration guide.
Take your time and check every step
A safer way to migrate your wallet
Rushing can cause further issues. Set up the new wallet, confirm you can receive and recover it, and only then move your full balance.
- 01
Check the old backup
Ensure your written backup and wallet fingerprint match the wallet currently holding your funds.
- 02
Install and verify the fixed firmware
Use the right model and firmware track. Check the official download and confirm the version on your device before generating a new seed.
- 03
Generate a brand new seed
Use the updated COLDCARD process or another hardware wallet you’ve reviewed. Don’t reuse or import your old seed words.
- 04
Back up your new wallet securely offline
Carefully record your new seed. If you use a passphrase, back it up precisely and keep it separate.
- 05
Check fingerprint and receiving address
Restart the device, check the expected wallet fingerprint, and compare a receiving address on the hardware wallet’s display.
- 06
Send a small test amount
Send a small amount from your old wallet and check that the new wallet receives it and can be restored.
- 07
Transfer the remaining balance
Only once the test is successful should you transfer the rest to the same verified new wallet.
- 08
Keep your old backup until confirmed
Don’t destroy your old recovery material until all expected transactions are confirmed and you’ve double-checked the new wallet.
Switching devices isn’t enough
Don’t restore the same affected seed on a different brand
The weakness is in the seed and all keys derived from it. Importing the same words into another device keeps the same keys. Generate a new seed and transfer your bitcoin as usual.
GhostlyInc editorial review
We would not select COLDCARD for a new wallet at present
A seed-generation flaw persisted in a critical security process for years, and the initial public review didn’t cover all models. This has significantly reduced our confidence. If buying new, we would now opt for a different device after reviewing its seed generation, recovery process, audit record, firmware support, and transparency.
This is our current editorial view, not a claim that every COLDCARD is unsafe or that other wallets are unbreakable.
Coinkite’s actions after disclosure
- Published technical details and clear migration instructions.
- Released fixed firmware for the affected models and tracks.
- Build checks were added and targeted independent validation of the fix was gathered.
- States that any remaining stock with vulnerable firmware was destroyed and shipments halted.
Those are meaningful steps, but they don’t erase the seriousness or the years when weak seeds could be generated.
Choosing another option
Compare trust models before purchasing
Trezor, BitBox, Blockstream Jade, Bitkey, and Ledger all use different hardware, firmware, backup, and trust models. We’re not declaring any automatic winners. Compare the points below and only buy from the manufacturer or a verified authorised seller.
Trezor Safe 3: our budget recommendation
The Safe 3 features a straightforward two-button layout, open-source construction, and an EAL6+ Secure Element for device authentication and added independent entropy. Opt for the Bitcoin-only version if you do not require support for other cryptocurrencies.
These are affiliate links and we may receive a commission at no extra cost to you. They will direct you to your local Amazon site. Only purchase if the seller is Trezor's official Amazon shop or an authorised reseller, then check the packaging and complete the device authenticity check before setting up.
Lessons beyond a single manufacturer
A hardware wallet is a system, not just a badge of security
Randomness is a core part of trust
Strong encryption and secure storage can’t save a key that was predictable at creation.
System composition must be tested
A secure component only helps if the released binary actually uses it. Build and linker outputs must be checked directly.
Open source increases transparency, not certainty
Public code allows for independent review, but doesn’t guarantee that every critical integration error will be spotted in time.
Recovery plans must include migration
A backup simply brings back the same keys. If those keys are insecure, proper recovery means generating new keys and moving your funds across.
Sources and verification
Latest guidance and incident evidence
Firmware advice may change. We reviewed the current status, migration steps, technical explanation, and independent reports as of 18 August 2026. Always check the official status before taking action.
FAQs
Will updating COLDCARD firmware make my old seed secure?
No. Fixed firmware only secures future seed generation. It does not alter an existing seed or its derived private keys. If your seed was created on affected firmware, follow the current migration advice unless the independent-dice exception definitely applies.
Which COLDCARD firmware versions resolved the RNG issue?
The published minimum fixed versions are Mk2/Mk3 4.2.0, Mk4/Mk5 standard 5.6.0, Q standard 1.5.0Q, Mk4/Mk5 Edge 6.6.0X, and Q Edge 6.6.0QX. Always check the latest official status before creating a new seed.
Will importing my seed into a different hardware wallet solve the problem?
No. The new device would generate the same private keys from the same words. You must create a brand new seed and move your bitcoin to an address from that new wallet.
Are dice rolls enough to make my COLDCARD seed safe?
Coinkite says the exception only applies if you added at least 50 fair, independent, private dice rolls during the original seed creation, and the sequence was never recorded or revealed. If you’re unsure about any part, follow the conservative migration route.
Did attackers compromise Bitcoin or ECDSA?
No. The issue was weak randomness during key creation. Bitcoin accepted valid signatures from keys generated from a smaller pool than intended.
Is it safe to buy a COLDCARD now?
The fixed releases include the published remedy, but no hardware wallet is without risk, and this incident has shaken our confidence. At present, GhostlyInc would select a different device for a new purchase after reviewing its security design, recovery process, audit record, firmware support, and ease of use.