Coldcard Emergency - MOVE YOUR BITCOIN NOW

— Critical Coldcard entropy bug: Seeds generated on Coldcard devices (MK3, MK4, MK5, Q) have weak entropy equivalent to an 8-character password, making them brute-forceable. MK3 is most severely affected with deterministic key regeneration.

— Immediate action required: Users with Coldcard wallets must move funds to new keys or different hardware wallets immediately. Delay increases risk of theft as attackers can regenerate keys in minutes once balances are visible on-chain.

— Safe recovery methods: Use Sparrow Wallet or Nunchuck to recover and move funds. If software wallet access is unavailable, import seed phrase directly. As last resort, transfer to trusted exchanges like River while setting up safer infrastructure.

— Multisig exposure: Coldcard keys in multisig setups should be treated as compromised. Pre-spend multisig is slightly safer due to key obscurity, but should still be cycled immediately upon next spend.

— Safer alternatives confirmed: Bitbox, Trezor, Keystone, and others confirmed safe. Moving forward, multisig setup across multiple vendors strongly recommended to avoid single-vendor dependency.

— Lessons on security culture: This represents the worst hardware wallet breach in Bitcoin history. Humility, open-source code review via AI tools, and rigorous red-teaming of all custody infrastructure are now non-negotiable practices.

— If you own a Coldcard, locate your hardware wallet and associated software wallet immediately. Use Sparrow Wallet to scan for all funds tied to your keys and transfer them to new seed phrases on alternative hardware (Bitbox, Trezor, Keystone) or Nunchuck multisig setups within hours, not days.

— Transition to multisig architecture with multiple vendors and custody methods. Multisig does not require complex infrastructure; tools like Nunchuck make it accessible. Store wallet files securely in multiple encrypted locations (e.g., Proton Mail) to avoid vendor lock-in.

— Treat this as a red-team wake-up call: before deploying any hardware or software wallet, use AI code analysis tools (Claude, DeepSeek) to audit entropy generation and cryptographic primitives yourself. Do not assume vendor expertise; verify directly.