According to CoinMeta, the security of cold wallets has been questioned, with users of Ledger and Coldcard experiencing theft of their encrypted assets even when not connected to the internet. In July 2026, attackers exploited a previously introduced vulnerability to steal Bitcoin from addresses associated with Coldcard hardware wallets, resulting in losses of over $100 million. A survey of Galaxy Research revealed that the mnemonic phrases generated due to firmware errors on the affected devices lacked randomness, allowing attackers to reproduce these phrases and identify vulnerable wallets. Additionally, Ledger also exposed another threat involving genuine hardware wallets that were physically modified before being resold. Users should purchase hardware directly from manufacturers or trusted distributors and carefully check for any abnormal behavior during the setup process.