Firmware Updates on Air-Gapped Devices
A practical walkthrough of updating Coldcard and similar air-gapped hardware wallets without connecting to the internet — what to verify before and after.
Air-gapped devices trade convenience for isolation. That isolation breaks down when firmware grows stale and known vulnerabilities accumulate. Updating without a network connection is straightforward once you understand the manufacturer’s intended path.
Before you begin
Download the signed firmware package on a separate machine. Verify the hash against the value published on the manufacturer’s website using a second source if possible. Transfer via microSD card, not USB, for Coldcard units.
During the update
Never update immediately before a planned transaction or during a period of market stress. Schedule updates during calm weeks and confirm your seed backup is current and readable beforehand. If the update fails, you recover from seed — but only if the seed is intact.
After the update
Confirm the version number on device matches your expectation. Generate a test address and compare it against a previously recorded address for the same derivation path. A mismatch means stop and investigate before moving funds.
When to book help
If you have never updated firmware independently, or if your device is more than two major versions behind, a hardware wallet audit session covers the update as part of verification. We use our isolated test environment so your primary device is never the first to run new firmware.