Major Security Breach: Coldcard Hardware Wallet Vulnerability Puts Millions at Risk

A sustained exploit targeting Coldcard hardware wallets is escalating, with potential losses estimated to reach approximately $114 million, according to crypto security watchdog MyXmr. On-chain data points to one of the most significant hardware wallet security incidents in recent memory.

Attack Vector: Single-Signature Wallets in the Crosshairs

Alex Thorn, Head of Research at Galaxy Digital, provided analysis indicating attackers are executing “sweeping” operations. This method attempts to drain all funds from vulnerable addresses in a single transaction.

A critical pattern has emerged: The exploit appears to specifically target single-signature Bitcoin addresses generated by Coldcard devices. Multi-signature setups have not been reported as compromised so far, suggesting the vulnerability may be isolated to a specific aspect of single-signature address generation or transaction signing.

Immediate Action Required for Users

If you are using a Coldcard wallet, particularly in single-signature mode, take these steps immediately:

  • Verify Your Holdings: Use a blockchain explorer or a trusted wallet interface to check balances and transaction history for all addresses created by your device.
  • Move Your Funds Promptly: Transfer any remaining assets from potentially vulnerable addresses to a new, secure address generated by a different, unaffected device or application. Do not delay.
  • Stop Using the Device: Suspend using the hardware wallet for new transactions until the manufacturer releases an official fix and security advisory.

Current Status: Assessments Rely on On-Chain Intelligence

It's important to note that the loss estimates are primarily derived from researchers analyzing suspicious transaction patterns on the blockchain. The absence of widespread public reports from direct victims means the exact number of users affected and the final toll remain unclear.

Complicating the assessment, some flagged “sweeping” transactions are still unconfirmed, making real-time loss calculation challenging. The community and analysts are closely monitoring for their final settlement.

This incident serves as another stark reminder for cryptocurrency holders: hardware wallets are not impenetrable vaults. Potential flaws in firmware, random number generators, or accompanying software can create exploitable weaknesses. Staying informed about device security and being prepared to act swiftly in a crisis are essential components of self-custody.