Coldcard Fourth Wave Hits 462 Wallets-Another 450 BTC Could Vanish in Hours

The suspected fourth wave puts another ~449 BTC in play

Another 448.73 BTC tied to 462 suspected victim addresses is the main near-term figure investors are watching. Galaxy's Alex Thorn said the fourth wave is still "likely" unfolding, which means total losses could rise while transactions remain unconfirmed.

Why the toll can still rise

The key mechanism is Replace-by-Fee. When competing transactions are still sitting in the mempool, the next confirmation can be outbid rather than simply waited out. Thorn has said similar transactions remain pending, so the damage tally can still change quickly.

The sweeps are already moving fast

Between blocks 960,778 and 960,792, 218 transactions moved over 380 BTC to 210 new addresses. That pace points to an active sweep rather than a slow, passive drain.

Cumulative exposure is already substantial

Earlier waves had already been linked to 1,367.05 BTC from 4,585 addresses, with confirmed losses at $88.6 million. A fourth wave that is still unfolding raises the risk that total losses climb further.

Coldcard's firmware flaw makes offline target screening possible

The pressing question is not whether the attacker has momentum. It is how the attack can keep finding targets without directly compromising users' devices.

How the offline guess works

The issue traces back to a March 2021 firmware integration error that routed Coldcard seed generation to a software pseudorandom number generator instead of the STM32 hardware RNG. In practice, that meant some wallets did not use the entropy source they were supposed to.

Once that happened, the attack became a verification problem rather than a remote hacking problem. According to Block, an attacker who can constrain the device UID, timer state, and prior RNG-call history can reproduce candidate output streams offline, then derive addresses and compare them with public blockchain data.

Patched firmware does not fix already-generated seeds

Coinkite shipped emergency firmware, but it also said installing the patch does not repair an existing seed. If a seed was created through the vulnerable path, the weakness travels with it.

That means exposure depends on when the seed was generated, not what firmware is on the device today. Affected users are told to generate a new seed on patched firmware and move their funds. Even restoring an old seed onto updated firmware carries the weakness forward.

Why the target pool remains large enough to matter

Coinkite estimates roughly 40 bits on the Mk3 and about 72 bits on the Mk4, Mk5 and Q, versus 128 bits for a standard 12-word BIP-39 seed. That does not mean every wallet is trivial to compromise, but it does mean the search space is materially smaller than intended.

The latest activity already touched 709 potential victim addresses, which suggests the attacker still has enough publicly visible targets to keep screening offline. Even so, No public report has reconstructed a victim's seed and matched it to a drained address, so the exact practical scale of the attack remains hard to verify.

What matters most now: mempool contests, new destinations, and whether the wave stalls

Bitcoin's Replace-by-Fee feature means the next confirmation can be outbid, and Thorn said victims with pending transactions may still have a brief chance to move their funds ahead of the attacker. That creates a narrow window between spotting a sweep and losing the race for confirmation.

The signals to watch

What matters now is not just the final damage total. It is whether similar transactions in the mempool are still being replaced with higher-fee versions. If those contests are still happening, coins are still trapped in the confirmation queue and can still be rescued or stolen.

Watch three things closely:

• More RBF replacements: the race is still live and victims still have a path to outrun the attacker.
• New clean destinations: fresh receiving addresses usually mean funds are being staged for movement.
• Fewer pending outputs: that can mean the pool of rescueable coins is drying up.

Where pressure could spread if funds are stolen

If the attacker confirms before victims can outbid them, the next risk is what happens to the stolen coins. Thorn said Some funds have already been swept into second-hop addresses, which suggests at least some of the stolen BTC is already being moved around rather than left idle.

This also matters because Coldcard has halted shipments and said patched firmware protects only newly generated seeds. That limits immediate replacement demand, but it does nothing to stop existing holders from trying to move funds to fresh wallets now.

The clearest sign the wave is losing momentum

The simplest reversal signal is also the easiest to watch: no new RBF contests, no fresh destination clustering, and no fresh sweeps for a few blocks in a row. If that happens, the immediate risk of more forced losses starts to fade. If it keeps happening, the market should assume the attack still has work left to do.