$38M in Bitcoin swept: Coldcard Mk3 users urged to act

Nearly 594 BTC were swept from 500 dormant wallets, prompting Coinkite to warn Coldcard Mk3 users of a possible seed flaw. No direct link is confirmed, but users are urged to migrate funds.

A coordinated sweep saw approximately 594 BTC, valued at around $38 million, moved from nearly 500 single-signature Bitcoin addresses within a short timeframe. Many of these wallets had been dormant for years, each containing between 0.15 and 0.26 BTC. This incident coincided with warnings from Coinkite, the maker of Coldcard hardware wallets, advising Mk3 users running firmware versions 4.0.1 to 5.0.3 to migrate their funds due to a potential seed generation vulnerability. While some reports suggest a flaw in Coldcard's key generation process may be involved, there is no definitive public evidence directly linking the vulnerability to the sweep. Coinkite clarified that Mk4, Q, and Mk5 models are unaffected, and wallets using a BIP-39 passphrase face minimal risk. The company recommends generating new seeds on unaffected devices and following secure migration procedures. Investigations into the cause of the sweep are ongoing.