Canadian manufacturer Coinkite has issued a precautionary security advisory for COLDCARD Mk3 users, warning that wallet seeds generated in firmware versions 4.0.1 through 5.0.3 may be vulnerable, potentially putting associated Bitcoin funds at risk.
According to the company, preliminary analysis suggests the COLDCARD Mk4, Mk5 and Q models are unaffected.
Users who secured affected wallets with a BIP-39 passphrase are believed to face only minimal risk, while those still relying on Mk3 devices are encouraged to create a new passphrase-protected wallet or migrate to new seed generated on unaffected hardware.
Coinkite urged users to migrate cautiously by generating a new seed on a newer COLDCARD device, verifying wallet backups and addresses, and testing transfers before moving larger balances.
For experienced users, the company also outlined a dice-roll seed generation method that avoids the Mk3’s random-number generator.
Coinkite said it is continuing to investigate the issue and plans to release a detailed technical analysis.
Launched in 2019, the COLDCARD Mk3 is Coinkite’s Bitcoin-only hardware wallet designed for advanced users, offering air-gapped transaction signing, open-source firmware, and a range of security features aimed at protecting private keys.
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