Nunchuk Issues Guidance on Coldcard Security Incident, Recommends Immediate Migration for High-Risk Multisig Wallet Users

Odaily News: Bitcoin wallet service provider Nunchuk has issued an important update regarding the recent Coldcard security incident, recommending that users with multisig wallets containing Coldcard-generated keys migrate their funds as soon as possible.

Nunchuk has categorized response levels based on the number of affected Coldcard keys in a multisig wallet: if the number of Coldcard-generated keys has reached the signing threshold, attackers could theoretically transfer funds directly, and such users should migrate immediately; if the wallet contains only 1 Coldcard-generated key and it is below the signing threshold, a single compromised key cannot move funds independently, making the risk relatively lower, but migration is still strongly recommended. If users cannot confirm the exact number of Coldcard keys in their wallet, they should treat it as a high-risk situation.

Additionally, Nunchuk announced that an upcoming mobile update will automatically enable the Slipstream channel for paid users. At that point, any auxiliary multisig wallet transaction containing at least one Coldcard key will bypass the public mempool and be submitted via Slipstream, reducing the risk of transaction monitoring and replacement. For users who wish to act immediately or for free-tier users, Nunchuk offers a manual migration option: users need to create a migration transaction, complete multisig signing without broadcasting, and then submit the raw transaction data to the Slipstream platform.