The Coldcard Flaw Exposes a Testing Gap No Hardware Wallet Buyer Can See

When a hardware wallet fails, the first questions are usually about money: how much was taken and whether it can be recovered. The Coldcard incident of 2026 raises a harder question about process. Kraken chief security officer Nick Percoco, quoted by Cointelegraph, called the flaw a wake-up call for the entire category, and his reasoning deserves attention beyond this one product.

The component nobody could check

Percoco’s core argument is that the failure was not just a bug but a blind spot in how these devices are validated. Code reviews of Coldcard would have confirmed that its true random-number generator code existed and functioned. What no review checked was whether that generator was the source actually being called when production firmware created a seed.

In the affected builds it was not. As The Hacker News described, the firmware fell back to a predictable value, producing seeds with roughly 72 bits of entropy instead of the intended 128. The strong randomness the device advertised was present in the codebase but bypassed in the execution path that mattered.

Percoco framed the consumer’s position bluntly: buyers are asked to trust a manufacturer’s implementation of the single most critical function in the system, with no independent verification that the approved entropy path is the one actually executing. A shopper comparing hardware wallets has no way to test this. It is invisible at the point of purchase and invisible in daily use, right up until funds disappear.

Standards already exist elsewhere

The frustrating part, Percoco noted, is that the security industry already has answers for this problem. He referenced two published standards:

• NIST SP 800-90B, a United States government specification for designing, testing and validating the entropy sources used in cryptographic systems.
• BSI AIS-31, a comparable standard from the German Federal Office for Information Security.

These frameworks exist precisely so that a random-number generator can be independently evaluated rather than taken on faith. Applied to hardware wallets, they would test not only that a strong entropy source is present, but that it is the one feeding key generation in shipped firmware. The Coldcard episode suggests that level of validation has not been standard practice across the wallet category, even though the assets at stake are substantial.

How fast the exploit spread

The case for stronger validation is reinforced by how the attack unfolded once the weakness was understood. Research from Galaxy, cited by Cointelegraph, found that at least 15 separate attackers exploited the Coldcard vulnerability. This was not a single sophisticated group with a private edge. It was a reproducible flaw that multiple independent parties could act on simultaneously.

That is the signature of a weak-entropy problem. Because the reduced search space is the same for everyone, any attacker who understands the pattern can generate candidate keys and sweep vulnerable wallets. The Hacker News reported that some wallets were drained in a matter of minutes. When exploitation is both reproducible and fast, the window for defenders to react is short, and the value of catching the flaw before shipping is correspondingly high.

What buyers and builders should take from this

For wallet makers, the implication is direct: independent entropy validation against an established standard should be part of the release process, not an afterthought. Demonstrating that the approved randomness path is the executing one closes exactly the gap that this incident exposed.

For users, the lesson is that no single device should be a single point of failure. Practical responses include:

• Adding verifiable randomness to seed generation, such as combining device output with dice rolls, so the outcome does not depend entirely on one implementation.
• Layering a passphrase on top of the device seed, which changes the resulting keys even if the base seed is weak.
• Using multisignature setups that combine independently designed devices and independently generated entropy, so a flaw in one product cannot drain funds alone.

None of these steps require abandoning hardware wallets, which still serve their primary purpose of keeping keys off internet-connected machines. They acknowledge a more subtle reality: the guarantee a hardware wallet offers is only as strong as its least verifiable component.

Bottom line

The Coldcard flaw was a failure of randomness, but its lasting significance is about verification. A critical function was trusted without an independent test confirming it worked as described, and standards that could have caught the problem already existed. Until independent entropy validation becomes routine across the category, the safest posture for holders is to assume any single device can fail and to build custody that survives it.

Sources and review

This article was checked against the primary or authoritative sources below .

• Coldcard Flaw Exposes Hardware Wallet Testing Blind Spot: Kraken — Cointelegraph
• At least 15 attackers exploited Coldcard vulnerability: Galaxy — Cointelegraph
• Coldcard Hardware Wallet Flaw Linked to $70 Million Bitcoin Theft in 41 Minutes — The Hacker News

Frequently asked questions

What is the testing gap the Coldcard hack revealed?

According to Kraken security chief Nick Percoco, code reviews confirmed that Coldcard's true random-number generator code existed, but there was no independent test verifying that this generator was the one actually being called by production firmware to create keys.

Are there existing standards for testing randomness?

Yes. Percoco referenced NIST SP 800-90B in the United States and BSI AIS-31 in Germany, which specify requirements for designing, testing and validating physical random-number generators used in cryptography. He noted such checks are standard elsewhere in the security industry.

How many attackers exploited the flaw?

Research cited by Cointelegraph from Galaxy found that at least 15 separate attackers independently exploited the Coldcard vulnerability, showing how quickly a weak-entropy discovery spreads once understood.

Does this mean hardware wallets are a bad idea?

No. Hardware wallets still remove private keys from internet-connected devices, which defends against many common threats. The point is that a single unverified component can undermine that protection, which argues for defense in depth rather than abandoning cold storage.