Firmware timeline

The vendor advisory starts at v4.0.1; source evidence includes v4.0.0 Both the Mk3 advisory and the technical backgrounder, in the versions held here as of 2 August 2026, give the affected range as "4.0.1 (March 2021) through 4.x". Bitcoin Optech repeated it, citing the advisory. Neither boundary looks like a typographical slip: the advisory states 4.0.1 twice, and this site states 4.0.0 from the repository record. Coinkite has already revised this range once, from a first advisory state that ran the issue "through firmware version 5.0.3".

The release history in the vendor's own repository puts 4.0.0 on 17 March 2021 and describes it as "Major internal changes... all crypto and BIP39 related code replaced", which is the migration that introduced the bug. 4.0.1 did not arrive until 29 March, and its changelog entry is about something else entirely: "Fixes security issue in v4.0.0."

The 17 March release commit contains random.bytes(32), the defined-zero board macro, the vulnerable libngu revision and the MicroPython fallback revision. The signed-release record also lists the 4.0.0 image. Block's range starts at 4.0.0.

The evidence therefore supports classifying a seed generated on Mk2 or Mk3 v4.0.0 as affected, notwithstanding the narrower Coinkite wording. What it does not establish is distribution: the record shows that 4.0.0 was built and signed, not how many devices ran it during the twelve days before 4.0.1 superseded it.

One piece of outside evidence bears on the same boundary from a different direction. Chain analysis published by Galaxy Research on 1 August 2026 reports that no coin drained in its first three sweep waves was created before roughly block 674,951 on 17 March 2021, which is the v4.0.0 release date rather than the 29 March v4.0.1 date, so it corroborates a March 2021 onset without settling which of the two releases marks the boundary. Galaxy's wording is "The vulnerable Coldcard firmware shipped on March 17, 2021 around block 674,951. Not one of the coins we have identified in Waves 1-3 taken was created before that block."

Three limits belong with that. The block height is Galaxy's own approximation. The finding is about when coins were first received rather than about which firmware generated any particular seed, and Galaxy separately records that it has "not utilized compute to test whether the addresses we have identified as possible victims were indeed generated with low entropy". And twelve days is too narrow an interval for coin creation dates to separate 4.0.0 from 4.0.1, so an absence of earlier victim coins is consistent with the 4.0.0 boundary rather than decisive between the two. The classification above rests on the release commit, the pinned libngu revision, the defined-but-zero board macro and the signed 4.0.0 image; this is corroboration of a March 2021 onset set beside that evidence, not a replacement for it.