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A security breach at Coldcard sent shockwaves through the Bitcoin world. Around 233,000 bitcoins — worth roughly $15 billion — shifted hands almost immediately after the wallet hack became public knowledge, per Casa CEO Nick Neuman.
That’s not a small number. These weren’t day traders panicking over a price dip. The bitcoins involved had been sitting still for over 155 days, which puts them squarely in the hands of serious, long-term holders — the kind of people who don’t move funds lightly. Some of those transfers, Neuman noted, didn’t even come from Coldcard users directly. The fear spread wider than the breach itself, pulling in holders who weren’t technically at risk but weren’t willing to find out the hard way. Long-term holders as a group cut their reserves from nearly 15 million bitcoins down to 14.7 million — the steepest weekly drop since December 2024. That’s a dramatic shift in a very short window.
Ledger and Trezor Users Scramble for Multisig Cover
Ledger and Trezor users didn’t wait around. Spooked by what happened to Coldcard, many started migrating toward multisig setups, basically splitting custody across multiple keys and devices so no single point of failure can drain a wallet. It’s a more complicated setup than most casual holders bother with, but the Coldcard breach made the tradeoff feel worth it fast.
Neuman’s read on all of this was pretty direct. He said the movement of funds actually shows that distributed self-custody systems work — they’re a protective layer, not a weak spot. When one hardware wallet gets compromised, holders who’ve spread their risk across multiple solutions aren’t left completely exposed. The mass migration, in his view, was the system doing exactly what it’s supposed to do.
Still, the scale of the reaction says something about how rattled the community got.
A 5-Year-Old Flaw Found by AI
Here’s where it gets uncomfortable. Ledger’s CTO, Charles Guillemet, said the flaw in Coldcard’s wallets had been sitting in public code for five years. Five years. Nobody caught it — not through manual review, not through routine security checks. It took AI tools to surface it.
Ian Rogers of Ledger weighed in on what that means for the broader threat picture. His point was that AI doesn’t create new vulnerabilities — it finds existing ones faster. That’s a subtle but important distinction. The flaw was always there. AI just made it possible to locate it before, or in this case, around the same time, that someone with bad intentions could.
That’s the uncomfortable math now facing every open-source project in the Bitcoin ecosystem. Transparency is supposed to be a feature of open-source code — anyone can look, anyone can spot problems. But “anyone can look” now includes AI systems scanning thousands of lines of code in minutes. And not everyone looking has good intentions.
Guillemet’s warning was clear: companies need to audit sensitive code before attackers do. Proactive review, not reactive patching. The window between a vulnerability existing and a vulnerability being exploited has probably shrunk considerably.
What This Means for Hardware Wallet Security
The Coldcard incident doesn’t mean hardware wallets are finished. It’s more complicated than that. No security setup is fully bulletproof — that’s been true forever in this space. But the breach does push the conversation away from “which hardware wallet should I trust” toward “how do I structure custody so one failure doesn’t cost me everything.”
Diversifying wallet manufacturers matters. Using multisig matters. Regular, rigorous code audits matter — maybe more than anything else right now. The five-year dormancy of that flaw in publicly available code is a hard lesson about what “open source” actually means in practice. Transparent code isn’t automatically safe code. It’s only safer if people — or now, AI tools — are actually looking at it regularly.
The crypto security community is probably going to be doing a lot of looking in the coming months. Developers across the hardware and software stack are now under pressure to run their own AI-assisted audits before someone else does it for them and finds something ugly.
It’s worth being honest about what’s still unclear here. The source didn’t specify exactly how the breach was executed or which specific Coldcard models were affected. No details on whether Coldcard has patched the flaw or issued a formal timeline for remediation. Unclear whether any funds were actually stolen or whether the 233,000 bitcoin movement was purely precautionary.
What is clear: long-term Bitcoin holders moved fast, Ledger and Trezor users followed, and the industry’s conversation about AI-assisted vulnerability discovery just got a lot more urgent.
Neuman put the total movement at roughly $15 billion worth of bitcoin shifting in the aftermath of a single hardware wallet breach.
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Frequently Asked Questions
How much Bitcoin moved after the Coldcard hack?
Around 233,000 bitcoins, worth approximately $15 billion, moved following the breach, per Casa CEO Nick Neuman.
How was the Coldcard vulnerability discovered?
Ledger’s CTO Charles Guillemet said AI tools identified a flaw that had been dormant in Coldcard’s public code for five years without being caught through conventional review.
