Coldcard Security Alert: Move Your Bitcoin Now

Coinkite is urging Coldcard users to move their funds immediately after identifying a serious security flaw. The issue affects how seed phrases were generated on certain firmware versions. Specifically, Mk3 devices running firmware since version 4.0.1 have reduced entropy, making them vulnerable to attackers who can predict private keys. Other models including the Mk4, Mk5, and Q devices also carry risks if they used older firmware versions.

The alert follows a massive security breach where 594 BTC disappeared from roughly 500 wallets. Analysts tracked the theft across several blocks, noting that the attackers drained single signature wallets while avoiding multisig and Taproot setups. The stolen funds are worth roughly 38 million dollars at current market rates, with some individual victims losing nearly 30 BTC in the process.

To protect your assets, Coinkite recommends generating an entirely new seed on an updated device. Mk4 and Mk5 users should first update to firmware version 5.6.0 or newer, while Q users need version 1.5.0Q. If you are stuck using a vulnerable Mk3, add a strong and unique BIP 39 passphrase immediately to add a layer of security. Always verify your receive addresses and conduct a small test transaction before moving your full balance.