Coldcard

Overview

Coldcard is a Bitcoin hardware wallet made by coinkite, designed for air-gapped / offline seed generation and signing.

Recent Developments

• 2026-07-30: Attacker drains 1,083 BTC ($70M per galaxy-research) from 1,196 wallets in ~41 minutes by exploiting firmware RNG fallback — no physical device access (2026-08-01-coldcard-firmware-rng-70m-bitcoin-drain)
• Root cause: yasmarang-rng software fallback when hardware RNG macro mishandled (2026-08-01-block-coldcard-rng-advisory)

Warning

coinkite emphasizes Mk3-focused warnings; block places Mk2/Mk4/Q/Mk5 in broader scope. Loss figures revised from ~$38Mearlytalliesto$70M Galaxy map.

• Firmware patches do not repair already-generated weak seeds — users must migrate funds

Related

• coinkite
• hardware-wallet-security
• yasmarang-rng
• bitcoin-self-custody
• block
• galaxy-research

Sources

• 2026-08-01-block-coldcard-rng-advisory
• 2026-08-01-coldcard-firmware-rng-70m-bitcoin-drain