A firmware integration error in some Coldcard hardware wallets could cause new recovery phrases to be generated without the intended hardware random-number source, according to a notice from Coldcard and a technical analysis by The Block. The failure could send the device into a software-based random-number path that was more predictable than the wallet’s designed security model, weakening private keys from the instant a mnemonic phrase was created.
The issue affects the most sensitive stage of self-custody: generating the secret entropy from which a wallet derives its private keys. A recovery phrase stored securely on paper or steel cannot compensate for poor randomness at creation, because every address and signing key generated from that phrase inherits the original weakness.
Coldcard’s disclosure placed the focus on a practical challenge for hardware-wallet users. A device can remain offline, use a secure element, and run publicly inspectable code, while an error in the path connecting those components can still undermine its default setup process. Users generally cannot test whether a device accessed its physical entropy source when creating a seed.
Seed generation sits below every later security decision
Hardware wallets are designed to protect private keys from internet-connected computers and malware, while giving users direct control over the credentials needed to authorize on-chain transactions. That protection relies on the wallet producing unpredictable cryptographic material in the first place.
Random-number generation is central to that process. A wallet turns random data, often called entropy, into a standard mnemonic phrase such as a 12- or 24-word recovery backup. If an attacker can narrow the range of possible entropy values, they may be able to derive or guess a victim’s private keys far more efficiently than cryptographic assumptions allow.
The reported Coldcard issue involved the integration of a hardware random-number generator rather than the concept of hardware wallets broadly. Hardware randomness normally derives unpredictability from physical processes in a chip or component. A software fallback may be useful when carefully designed and combined with independent sources of entropy, but a predictable fallback defeats the purpose when it becomes the only effective source.
The Block’s technical analysis described a scenario in which users could follow the ordinary setup flow and receive a mnemonic affected by the flaw. That makes the incident more serious than an advanced configuration error, because default behavior is the security boundary most customers depend on.
Coldcard’s notice means users who created a seed on an affected device should treat the old mnemonic as potentially compromised until they have established whether their setup was exposed. Applying a firmware update can correct the software running on the device, but it cannot add entropy retroactively to a phrase generated under defective conditions.
Moving funds requires a newly generated seed
The practical remedy for an exposed wallet is to generate a completely new recovery phrase after installing the relevant fix and then transfer funds to addresses derived from that new seed. Reusing the old mnemonic, even on updated hardware or another wallet application, retains the same underlying key material.
Users should verify the new backup before moving substantial balances. That means confirming that the recovery phrase can restore the wallet through a compatible tool or a controlled recovery procedure, rather than assuming that a handwritten backup is readable and complete.
The episode also reinforces the need to review transaction details before approving a signature. A sound seed-generation process protects against one category of failure, while malicious address substitution, unsafe backup handling, phishing and incorrect transaction approvals remain separate risks.
For people holding substantial balances, spreading operational risk can be more useful than relying on a single product or backup method. Separate devices, independently stored backups and carefully designed multisignature arrangements can limit the damage from a failure in one wallet, one location or one key.
Multisignature wallets require several distinct keys to approve a transaction. A 2-of-3 arrangement, for example, can require two signatures from three separately controlled keys. If implemented with devices from independent vendors and stored in different locations, that structure can reduce exposure to a single firmware defect or hardware failure. It also creates more operational complexity, including the need to preserve configuration information and ensure every signer can be recovered.
Custody debate cannot be reduced to loss totals
The Coldcard disclosure resurfaced a familiar dispute over whether users are safer holding Bitcoin themselves or leaving it with a centralized custodian. Changpeng Zhao, the former chief executive of Binance, cited River’s Bitcoin Custody Report 2025 in arguing that historical loss figures favor trading platforms over individual self-custody.
River’s report itself cautioned against treating its historical estimates as a complete comparison. It said most permanently lost Bitcoin was lost before 2020, when wallet tools and custody practices were less mature. It also said exchange losses are difficult to measure fully, that some customer losses may have been reimbursed, and that cumulative figures are not adjusted for the amount of Bitcoin held or the length of time it was held.
Those limitations leave two different questions that are often merged into one. One concerns the probability that a user loses keys or makes a personal security mistake. The other concerns access during platform stress, account restrictions, withdrawal suspensions or a custodian’s operational failure.
Centralized custody can remove much of the burden of seed storage, wallet setup and transaction signing from the individual. In return, the customer depends on the platform’s security controls, solvency, withdrawal policies and ability to continue serving the account. Self-custody gives the user final authorization over the coins, but requires them to manage backups and choose tools carefully.
A properly backed-up self-custody wallet can generally be recovered in compatible software or hardware even if the original manufacturer closes or discontinues a product. That portability is one of the model’s strengths, though the Coldcard incident shows why portability does not eliminate risks embedded in the first creation of a seed.
Security products face a higher default-path standard
Hardware-wallet makers market themselves as trust-minimizing tools, yet users must still place trust in manufacturing, firmware releases, supply chains and testing. Open-source code can support independent scrutiny, but few customers are able to reproduce firmware builds, inspect random-number behavior or validate every hardware interaction before creating a wallet.
That raises the standard for vendors when a flaw is discovered. Clear identification of affected versions, direct guidance for existing seed holders, reproducible fixes and timely disclosure give users the information needed to move funds before uncertainty turns into a loss.
For users, the immediate lesson is narrower than abandoning self-custody or treating any custody model as universally safer. Security depends on how keys were created, where backups are held, whether recovery has been tested, and whether a single failure can permanently block access or authorize a transfer. The Coldcard case shows that a hardware wallet’s strongest promise begins before the first transaction: with the randomness used to create the wallet itself.
For a deeper look at wallet safety and seed protection, explore our guide on crypto wallet mistakes to avoid today.
Disclaimer: The content on this page is provided for general informational purposes only and does not represent the views or financial advice of Toobit. We make no guarantees regarding the accuracy or completeness of this information and shall not be held liable for any errors, omissions, or outcomes resulting from its use. Investing in digital assets involves risk; users should independently evaluate their financial situation and the risks involved. For further details, please consult our Terms of Service and Risk Disclosure.
