Urgent wallet safety guide
COLDCARD Vulnerability 2026: Check Your Seed, Not Just Your Firmware
A firmware update can fix new seed generation, but it cannot strengthen a seed that was already created with weak randomness. If your current seed came from affected COLDCARD firmware, check the steps below and migrate carefully.
Read this before changing anything
Updating the device does not repair the wallet you already use
The firmware fix changes how future seeds are created. It does not change the words, private keys, or addresses derived from an existing affected seed. Unless the official independent-dice exception clearly applies, create a completely new seed and transfer the funds to it.
Table of Content
Affected models and releases
Compare the firmware that created the seed
The version installed today is only half of the answer. You need the model, the release track, and the firmware that was running when your current seed was first generated.
| Model and track | Affected seed generation | Minimum fixed release for new seeds |
|---|---|---|
| Mk2 / Mk3 | Seeds created on firmware 4.0.1 through 4.1.9 | 4.2.0+ |
| Mk4 / Mk5 standard | Seeds created before the fixed standard release | 5.6.0+ |
| Q standard | Seeds created before the fixed standard release | 1.5.0Q+ |
| Mk4 / Mk5 Edge | Seeds created before the fixed Edge release | 6.6.0X+ |
| Q Edge | Seeds created before the fixed Edge release | 6.6.0QX+ |
Standard and Edge are separate tracks
An older Edge 6.x release is not automatically safe because its number is higher than a standard 5.x release. Match both the model and the track.
Some Coinkite products use different code
Coinkite says TAPSIGNER, OPENDIME, and SATSCARD are not affected by this seed-generation defect because they use different codebases.
Check the device
How to view the installed firmware
On current COLDCARD documentation, unlock the device and open Advanced/Tools, Upgrade Firmware, then Show Version. Compare the displayed model, track, and version with the current security status page.
Open the official current security statusThe question the menu cannot answer
Which firmware originally created this seed?Use your setup date, purchase date, release history, or your own records to narrow it down. If the seed may have been created on an affected release and you cannot prove otherwise, follow the conservative migration guidance.
Simple decision path
Do you need to migrate?
- 01
Was the current seed generated on a COLDCARD?
If no, this specific COLDCARD seed-generation defect did not create it. If yes or unknown, continue.
- 02
Was it created on an affected model and release?
Compare the original setup period with the affected matrix. The firmware installed today does not answer this question.
- 03
Were at least 50 fair, independent, private dice rolls added during original seed creation?
Coinkite says a seed meeting all of those conditions is not at risk from this RNG issue alone. Fewer rolls, exposed rolls, or uncertainty means you should continue to migration.
- 04
Was a strong and unique BIP-39 passphrase used?
It can slow an attacker, but it does not fix the seed. Unless the dice exception applies, plan a careful migration as soon as practical.
A strong, unique BIP-39 passphrase adds a separate barrier and can reduce immediate exposure. It still does not repair the underlying seed. Coinkite advises passphrase users to migrate as soon as practical unless the independent-dice exception applies.
What failed
Strong cryptography received weak starting material
Bitcoin and ECDSA were not broken. The problem happened earlier: some wallet seeds were created from a much smaller set of possibilities than users were promised.
Expected path
The dedicated hardware random generator should provide the unpredictable input used to create the seed.
Affected path
rng_get()→ngu.random.bytes()→Wallet seedA build and link integration error connected the seed-generation call to MicroPython's general-purpose software generator instead of the intended hardware implementation.
The engineering lesson
Source code can contain the right security component while the final build connects the wrong one.Open source, reviews, and reproducible builds improve verification, but they do not replace end-to-end tests of the actual call path and linked binary. The remediation now includes checks designed to reject the wrong RNG symbol during the build.
Why the numbers matter
128 bits, about 72 bits, and about 40 bits are not close
Each missing bit halves the number of possibilities an attacker must consider. A drop of dozens of bits changes a practically unreachable search into a serious security problem.
The intended minimum security level for the generated seed.
Additional secure-element input helped, but the result remained far below the target.
A dramatically smaller candidate space that created an urgent risk for funded wallets.
These are security estimates from the published incident analysis, not a promise that every device or seed has exactly the same search space. The practical instruction is unchanged: treat a potentially affected seed conservatively.
A real incident, not a laboratory warning
Reported thefts pushed the flaw into the open
Bitcoin Optech estimated that losses already exceeded 1,000 BTC on 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 raise the total to 2,055 BTC, but that wave still lacked 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 use different standards for victim confirmation. They are credible estimates, not a final proven total.
-
The faulty path enters seed generation
The libNgU migration changed the call path used to create wallet seeds.
-
The first public warning appears
The early advisory focused on Mk3 and initially treated newer models as outside the main risk.
-
The affected scope expands
Guidance was updated to include Mk4, Mk5, Q, and the separate Edge tracks; fixed releases were published.
-
Losses and technical causes are discussed
Coinkite acknowledged real harm and published more detail about the build, linker, and submodule boundary.
-
Current status and migration pages are consolidated
Coinkite published a clearer fixed-release matrix, targeted validation evidence, and a dedicated migration guide.
Move slowly and verify every handoff
A safer migration sequence
Rushing can create a second problem. Prepare the new wallet, prove that you can receive and recover it, and only then move the full balance.
- 01
Verify the old backup
Check that the written backup and wallet fingerprint match the wallet that currently controls the funds.
- 02
Install and verify fixed firmware
Use the correct model and release track. Verify the official download and confirm the version on the device before creating a new seed.
- 03
Create a completely new seed
Use the corrected COLDCARD flow or another hardware wallet that you have evaluated. Do not reuse or import the old words.
- 04
Back up the new wallet offline
Record the new seed carefully. If you use a passphrase, back it up exactly and separately.
- 05
Verify fingerprint and receive address
Power-cycle the device, confirm the expected wallet fingerprint, and compare a receive address on the hardware-wallet display.
- 06
Send a small test amount
Move a small amount from the old wallet and confirm that the new wallet receives it and can be restored.
- 07
Move the remaining balance
Only after the test succeeds, transfer the rest to the same verified new wallet.
- 08
Keep the old backup until confirmation
Do not destroy the old recovery material until every expected transaction has confirmed and the new wallet has been checked again.
Changing devices is not enough
Do not restore the same affected seed on a different brand
The weakness belongs to the seed and every key derived from it. Importing those same words into another device keeps the same keys. Generate a new seed and move the bitcoin with a normal transaction.
GhostlyInc editorial assessment
We would not choose COLDCARD for a new wallet today
A seed-generation failure remained in a security-critical path for years, and the first public assessment did not capture the full model range. That materially reduces our confidence. For a new purchase, we would currently choose a different device after checking its seed generation, recovery design, audit history, firmware support, and source transparency.
This is a current editorial judgment, not a claim that every COLDCARD is unsafe or that another wallet is impossible to break.
What Coinkite did after disclosure
- Published technical details and concrete migration instructions.
- Released fixed firmware for the affected model and release tracks.
- Added build checks and collected targeted independent validation of the remediation.
- States that remaining inventory with vulnerable firmware was destroyed and shipments were stopped.
Those are meaningful responses. They do not erase the severity or the years in which weak seeds could be created.
Choosing an alternative
Compare trust models before buying
Trezor, BitBox, Blockstream Jade, Bitkey, and Ledger use different hardware, firmware, backup, and trust models. We are not turning this incident into an automatic winner. Compare the points below and buy only from the manufacturer or a verified authorized seller.
These are affiliate links and may earn us a commission at no extra cost to you. They open your regional Amazon marketplace. Buy only when the seller is Trezor's official Amazon store or an authorized reseller, then inspect the packaging and complete the device authenticity check before setup.
Lessons beyond one manufacturer
A hardware wallet is a system, not a security label
Randomness is part of the root of trust
Strong encryption and secure storage cannot rescue a key that was predictable when it was created.
Composition must be tested
A secure component is useful only when the released binary actually calls it. Build and linker outputs deserve direct checks.
Open source improves visibility, not certainty
Public code makes independent review possible. It does not guarantee that the right reviewer will find every critical integration error in time.
Recovery plans must include migration
A backup restores the same keys. When the keys themselves are unsafe, recovery means creating new keys and transferring the funds.
Sources and verification
Current guidance and incident evidence
Firmware guidance can change. We checked the current status, migration instructions, technical explanation, and independent reporting on 18 August 2026. Recheck the official status before acting.
FAQ
Does updating COLDCARD firmware make my old seed safe?
No. Fixed firmware corrects future seed generation. It does not change an existing seed or the private keys derived from it. If the seed was created on affected firmware, follow the current migration guidance unless the independent-dice exception clearly applies.
Which COLDCARD firmware versions fixed the RNG problem?
The published minimum fixed releases 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. Check the current official status before creating a replacement seed.
Can I fix the problem by importing the seed into another hardware wallet?
No. The new device would derive the same private keys from the same words. Create a completely new seed and transfer the bitcoin to an address from that new wallet.
Do dice rolls mean my COLDCARD seed is safe?
Coinkite says the exception requires at least 50 fair, independent, private rolls added during the original seed creation, with the sequence never recorded or exposed. If any part is uncertain, use the conservative migration path.
Did attackers break Bitcoin or ECDSA?
No. The incident involved weak randomness during key creation. Bitcoin processed valid signatures from keys that came from a smaller-than-intended set of possibilities.
Is COLDCARD safe to buy now?
Fixed releases contain the published remediation, but no hardware wallet is risk-free and the incident damaged our confidence. GhostlyInc would currently choose a different device for a new purchase after comparing its security architecture, recovery model, audits, firmware support, and usability.