Bitcoin held broadly steady above $64,000 this weekend even as security researchers revealed the scale of a major hardware wallet exploit continued to grow, with the total amount stolen from Coldcard wallet users climbing to roughly $75.1 million as investigators traced additional theft transactions tied to the same underlying firmware flaw.

The attack began late Thursday, July 30, with an initial 25-minute sweep that drained approximately 594 bitcoin, worth about $38 million at the time, from around 500 single-signature wallets secured by Coldcard hardware devices. Galaxy Research, a blockchain analytics firm, later identified a second, larger wave of theft transactions tied to the same attacker, ultimately tracking a combined total of 1,158.66 bitcoin, worth roughly $75.1 million, taken from 2,673 separate wallet addresses across two related sweeps.

The vulnerability responsible for the theft traces back to a firmware integration error introduced in Coldcard firmware version 4.0.0 in March 2021, according to security analysis published by Block, the fintech firm founded by Jack Dorsey. The flaw caused affected devices to bypass their dedicated hardware random number generator, the component specifically designed to ensure a wallet's recovery seed cannot be predicted or reproduced by anyone other than the device's........

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