The Background

Hardware wallets were supposed to be Bitcoin’s fortress. Coldcard, in particular, was considered the gold standard—the choice of the paranoid, the “sleep at night” technology. Then the unthinkable happened.

Between July 30 and August 10, 2026, attackers drained 1,596 to 2,055 BTC—roughly $100 million to $130 million—from over 7,300 Coldcard wallets. No phishing. No physical access. No user error. Just a single misconfigured line of code that silently weakened seed entropy for five years.

And here’s where it gets ugly: the debate over how to fix this has ignited a firestorm between Bitcoin’s most influential voices. Ledger’s CTO says multisig isn’t the answer. CZ says nothing is 100% safe. And thousands of victims are left holding the bag. What you do next—and who you listen to—will determine whether your Bitcoin stays yours. Many are running back to what they believe to be safery with custodial options, which is definitely not the sollution but for many right now they on;y safe heaven they can undertand.

The Coldcard Collapse: What Actually Happened

Coldcard, the Bitcoin-only hardware wallet from Toronto-based Coinkite, had long been praised as one of the most secure self-custody solutions available. But a flaw in firmware version 4.0.0, shipped in March 2021, quietly disabled the hardware random-number generator.

Instead of the expected 128 bits of entropy for BIP-39 seed phrases, affected devices generated seeds with as little as 40 bits of effective entropy on Mk2 and Mk3 models. Later models improved to 72 bits, but that still falls short of cryptographic best practices.

Worse: if all multisig keys were generated on affected Coldcard devices, the attacker could brute-force them one by one. Simply exporting the seed to another wallet doesn’t fix the underlying vulnerability.

The attack unfolded in waves. The first drained 594 BTC (~$38 million) from 500 addresses in a single automated sweep. By August 2, Galaxy Research had tracked 1,367 BTC (~$86 million) across 4,585 addresses. A fourth wave added hundreds more. As of August 10, confirmed losses exceeded $100 million.

The Battle Over Multisig

This is where the controversy gets really interesting—and where the industry is tearing itself apart.

Team Multisig: “Singlesig Is Dead”

Joe Burnett, Vice President at Strive, stated that “a single hardware wallet generating one key for large Bitcoin holdings creates too much concentration risk”. His prescription: multi-vendor multisig, with keys generated independently on different hardware (meaning different trade marks) and software and stored in separate physical locations. This, in my opinion is the best option for those who wants to continue with self custody.

Even Coldcard’s own multisig wallet partners urged migration. Nunchuk issued an urgent alert for Coldcard multisig users. Casa CEO Nick Neuman reported that 233,000 BTC moved to safety after the exploit, with some of that flow reflecting holders shifting from single-key setups into multisig wallets.

Team Caution: “Multisig Isn’t Always the Answer”

Then came the counterpunch.

Charles Guillemet, CTO of Ledger—one of Coldcard’s biggest competitors—published a direct rebuttal: Bitcoin users do not need to rush to adopt multisig wallets. His argument? Making wallet setups more complex in the name of security can introduce new risks and make recovery and management harder. This statement, in my opinion, is absurd, any person who does self custody should do its home work and learn how to mulrisig or find a secure and insured custodial solution one of the two. I always with encourage self custody but I understand is not for everybody.

He pointed to Bitcoin miniscript as an alternative, allowing detailed spending conditions like inheritance rules and time-locked recovery keys. He also mentioned MuSig2, a cryptographic alternative to script-based multisig that—as far as he knows—only Ledger currently supports.

“We have to be careful not to confuse complexity with security,” Guillemet effectively argued. For most users, a properly backed-up single-signature hardware wallet remains the most practical option.

Important to mention that Ledger have been in the middle of previous scandals and I personally do not use their products nor recommend them.

The Broader Backlash

Binance founder CZ weighed in with a sobering reminder: “Nothing is 100%”. He suggested spreading funds across several wallets as one way to reduce exposure.

ARK Invest’s Lorenzo Valente went further, calling the self-custody hardware space “a disaster” and arguing that consumers have simply traded counterparty risk for “software risk, hardware risk, supply-chain risk, phishing risk, backup risk, and the possibility of losing everything through one mistake”. Hard to argue with his take…

Summary

Hardware wallets are not infallible as most poeple think they are. A single firmware bug can compromise years of “perfect” security. Self-custody may be too technically demanding for average users, pushing them toward ETFs and institutional custody. Even multisig isn’t a silver bullet if all your keys come from the same vulnerable vendor.

The Coldcard incident doesn’t disprove self-custody—it proves we need better systems. Multi-vendor multisig, collaborative custody, and improved entropy standards are the natural evolution of Bitcoin security. The market is already adapting: $626 million flowed into spot Bitcoin ETFs in the days following the attack, and the industry is finally having the hard conversations about independent audits and deterministic hardware testing.

My take: The question isn’t whether you can trust hardware wallets. It’s whether you can trust one hardware wallet from one manufacturer. Coldcard was considered the gold standard—and it just lost over $100 million of its users’ Bitcoin. If you’re holding significant Bitcoin, multi-vendor multisig isn’t optional anymore. It’s the minimum viable security. I really hope you get that securing your corn needs proper OPSEC and it is not convenient is doing your homework or trusting an insured third party with your funds.