Cold wallet compromised https://t.co/HBvkEaZUTf What happened? Grok 📕 This X post (@justh0dl, July 31, 2026) refers to a large-scale Bitcoin theft incident caused by a vulnerability in Coldcard hardware wallets. https://t.co/iVUi5B67ip What happened? Date and time: Early morning UTC on July 31, 2026 (~01:31–01:56) Details: Approximately **594 BTC** (valued at ~$38 million at the time) was stolen in a single sweep from around 500 single-signature wallets. The attack was completed in just about 25 minutes. Funds were drained across 500 transactions and then consolidated into a single address, where they remained stationary. Many victims were “Bitcoin-only” long-term holders who had stored their coins in cold storage—so-called “freezers” (ultra-long-term cold storage)—for years without moving them. Multiple reports indicate individuals lost their life savings. Cause: A flaw existed in the random number generation (entropy) during seed phrase creation for certain models and firmware versions of the popular Bitcoin-only hardware wallet, Coldcard (manufacturer: Coinkite). Seed phrases generated on Mk3 devices running firmware versions 4.0.1 (March 2021 onward) through 5.0.3 were particularly vulnerable. The seeds, which should have been completely unpredictable, were generated using predictable data such as the chip’s serial number, allowing attackers to reconstruct the private keys through computation. Some older firmware versions on Mk4, Q, and Mk5 devices were also mildly affected, but the primary impact was on Mk3 devices. As the poster noted, “the worst day for self-custody,” the shock stems from the fact that victims were not exchange users—they were users who had properly implemented cold storage. This incident differs fundamentally from FTX, which is the core point of the post. Coinkite promptly issued a security advisory, warning users with affected seeds to either add a passphrase and move their funds or migrate to a new seed phrase. https://t.co/H5u2IlazCZ While Bitcoin’s price was barely affected, the event has become a major topic of discussion in the community due to its significant blow to trust in self-custody.