Existing mnemonics cannot be fixed through updates; Coldcard reminds affected users to regenerate mnemonics and migrate assets

Odaily reported that Coldcard has released the latest firmware 5.6.1 (Mk4/Mk5) and 1.5.1Q (Q). This update is based on a three-week security review following the emergency fix on July 31, addressing security risks brought by the previous mnemonic generation attack. Each newly generated mnemonic must now include at least one source of user entropy, including at least 65 irregular keystrokes, 50 physical dice throws, or 128 physical coin flips, combined with fresh entropy provided by STM32 TRNG, SE1, and SE2. The new firmware also adds instant staged PSBT verification before signing, strengthens USB connection and firmware update boundaries, improves Delta Mode isolation mechanisms, fixes active wallet backup issues, enhances random number generator initialization and fault checking, adjusts SIGHASH default settings, and includes multiple security and correctness improvements. Coldcard stated that this update aims to further reduce the risk of device attacks. The official reminder notes that updating the firmware cannot fix existing mnemonics generated by previously affected firmware. If users' mnemonics fall within the scope of this security advisory, they should first update the device, then generate and verify a completely new mnemonic, and migrate funds to the new wallet. Coldcard recommends that all Mk4, Mk5, and Q users update their devices promptly and verify the signature of the downloaded firmware.