Coldcard users are fuming after a weakness known since 2021 allowed hackers to steal their Bitcoin. The cryptocurrency heist affects Coldcard – a small, physical device which stores private Bitcoin keys offline and signs Bitcoin transactions without the keys touching the internet. Researchers at financial services company Galaxy Digital noticed the initial theft which took place across a 41-minute window on 30 July. Coldcard users need to take actionBitcoin security experts at WizardSardine explained there is a saving grace for some Coldcard users: if none of a user's key was generated via a Coldcard itself, they’re safe. If this batch of attacks becomes confirmed, the total damages from the collective attacks would be roughly $181 million or 2,000 Bitcoin.