Coinkite released firmware version 5.6.1 for Coldcard Mk4 and Mk5 devices and version 1.5.1Q for Coldcard Q, requiring user‑supplied entropy for new seed generation to improve security. The update, announced in a Thursday blog post, follows a three‑week security review and adds safeguards for USB data handling, transaction signing and hardware randomness, including re‑verification of transactions before signing and additional randomness checks at boot. It mandates that newly generated seed phrases incorporate at least 65 keypresses with unpredictable timing, 50 dice rolls, or 128 coin flips, combined with the device’s built‑in randomness sources, to reduce vulnerability if a single entropy source fails. Coinkite urged users to upgrade immediately and to create new seed phrases, noting that existing seeds remain vulnerable even after the update. Reported losses from the earlier Coldcard exploit totaled 1,778 BTC, valued at about $112 million, according to a Galaxy Research report published Aug. 14, marking the third‑largest crypto exploit of 2026 per DefiLlama data. The prior July 31 update had already fixed seed‑generation failures for new wallets. Additional changes block certain Bitcoin signature hash modes that allow transaction outputs to be altered, restrict USB downloads to the latest device output, and require encrypted sessions. The update aims to improve the resilience of Coldcard wallets against potential seed‑generation weaknesses, but users must replace compromised seeds before moving funds.