Coldcard's 4th Wave Just Hit 462 Addresses-462 BTC at Risk in an $88M Hack

Coldcard fourth wave: still unfolding, still actionable

This is not a closed headline. It is a live drain.

TL;DR

The fourth Coldcard sweep is still unfolding, which means affected holders should act now rather than wait for full confirmation.

What changed in the latest wave

The key update is not whether the exploit existed. It is that the latest sweep covered 462 suspected victim addresses across 218 transactions, moved 388.93 BTC in roughly 2.5 hours, and spanned blocks 960778 to 969792. Even more important, more similar transactions may still be pending.

That is why the running total of stolen funds is now reported near $88.6 million in stolen funds. This remains an active extraction event, with fresh sweeps, fresh destination wallets, and some funds already moving beyond the first hop.

Yes, the weak-entropy flaw appears to have been patched. But patching the software does not undo damage already done. If you are in scope, check affected funds immediately. Some pending transactions may still be RBF-enabled, leaving a short window to outbid attackers before confirmation.

Why offline Coldcard wallets can still be drained

The attacker does not need to touch the device. They only need to reproduce the seed well enough offline.

The vulnerable seed path, in plain English

Block tied the exploit to a March 2021 firmware integration error that routed seed generation to a software pseudorandom number generator instead of the chip's hardware RNG. That fallback was initialized from the chip's unique ID and timer registers and collected no fresh entropy after initialization.

That changes the threat model. This is not a traditional remote hack. If an attacker can narrow the device UID, timer state, and prior RNG-call history, they can generate candidate seeds, derive addresses, and compare them with public blockchain data.

Why the patch helps going forward but does not fix old seeds

Exposure depends on the firmware running when the seed was created, not on the firmware installed today. Coinkite's update stops new weak seeds from being generated, but it does not repair a seed that was already produced in the vulnerable path.

That is why single-signature addresses can remain exposed even when the device is offline. Once the key material lives in a weak space, air-gapping does not reset that risk. The July 30 sweep is one example: the attacker drained 1,196 Bitcoin addresses in 41 minutes and took 1,082.65 BTC worth about $70.2 million.

The real risk metric is entropy

The more useful metric is effective entropy. Coinkite estimates roughly 40 bits on the Mk3 and about 72 bits on later models, versus 128 bits for a 12-word BIP-39 seed. That does not mean every old wallet is already drained. It does mean the weak space is small enough that vulnerable single-signature addresses remain at serious risk.

If you hold funds from a vulnerable Coldcard setup, the safer assumption is that the wallet is compromised now, not someday.

Is the exploit contained, or is damage still spreading?

The debate is not whether wallets were compromised. It is whether investors are already late.

The patch contains future risk, not past exposure

Bears can point to the fact that Coinkite shipped emergency firmware on July 31. That is true, and the fix does stop new weak seeds from being generated.

But "no new weak seeds" is not the same as "no more losses." The attacker has already shown that sweeps can move fast and keep expanding. Galaxy Research flagged a third wave of sweeps, and the fourth wave added another large sweep that pushed losses well past $88 million.

Why waiting for a cleaner signal is risky

The patch closes the source of new weak keys. It does not remove the risk to seeds already generated under the vulnerable configuration. Coinkite is clear that installing updated firmware does not repair an existing exposed seed, and restoring that old seed elsewhere carries the weakness forward.

If a vulnerable seed was used to create a single-signature wallet, the practical issue remains: as long as that seed can be reproduced or checked offline, the threat is still live.

What to do now if you may be affected

Treat this like a live drain, not a closed story.

Immediate steps

• Use patched firmware, then move. Coinkite's instruction is direct: owners with exposed seeds should generate a new seed on patched firmware and move their coins.
• Do not restore the old seed elsewhere. Putting that seed back onto updated firmware or into another wallet carries the same weakness forward.
• If a transaction is still pending, act quickly. Victims may still have a brief chance to outbid attackers using Replace-by-Fee.

What to watch next

• New sweeps are still appearing, and the fourth wave was still unfolding in recent updates.
• Some stolen funds have already moved beyond the first hop.
• The pattern still looks automated, with activity running at roughly 45 times the level seen in a prior control period.

If those signals fade, the immediate pressure may ease. If they continue, the window for damage control is still open.