ChainCatcher reports that Coinkite, a manufacturer of Bitcoin hardware wallets, disclosed in late July 2026 that a firmware build error introduced in March 2021 caused some Coldcard wallets to generate mnemonics from a smaller range, reducing the randomness of users' private keys. Galaxy Research researchers stated that exploitation of the Coldcard vulnerability occurred in multiple rounds, with observed Bitcoin losses increasing from approximately $88 million to nearly $114 million over several days. Following warnings from researchers that other vulnerable addresses could still be targeted, many Coldcard users transferred their Bitcoin. The Coldcard is a Bitcoin-only wallet that supports offline signing via microSD card and optional QR codes. Launched in 2017, it has long been regarded as one of the security-focused Bitcoin hardware wallets.
Coldcard Wallet Vulnerability Results in $114 Million in Bitcoin Losses
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Summary
Bitcoin news emerged after a firmware flaw in Coldcard wallets—first identified in March 2021—resulted in weak seed phrase randomness and $114 million in losses. Galaxy Research reported that the theft increased from $88 million within days. Coldcard, a Bitcoin-only hardware wallet since 2017, uses microSD cards and optional QR codes for offline signing. The incident adds to ongoing reports of vulnerabilities in the crypto space.
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