Coldcard Seed-Generation Flaw Drains 1,816 Bitcoin, Prompts Custody Reckoning

Coldcard Randomness Bug Becomes a Custody Reckoning

A seed-generation flaw in Coinkite's Coldcard hardware wallets let attackers drain approximately 1,816 bitcoin — about $116 million at the time — starting July 30, according to two independent outlets tracking on-chain security. One tally now counts nearly 1,200 drained addresses with confirmed losses near $70 million. The vulnerability sits in randomness used during key generation, so victims did not hand over a private key: drained addresses are enough when the entropy collapses.

The operational lesson is hard. Hardware-wallet users who relied on affected firmware versions must treat their seeds as exposed and migrate funds through a freshly generated wallet on a clean device, then re-anchor any multisig quorum to the new keys. For teams running self-custody at scale, the incident pushes entropy quality, firmware provenance, and supply-chain attestations back into the procurement checklist rather than the marketing slide.

A Separate March 2021 Firmware Bug Resurfaces at $38 Million

A different Coldcard firmware bug, originally shipped in March 2021, has now been linked to a $38 million theft from around 500 bitcoin wallets. The reuse of an old vulnerability for a fresh drain sharpens the point: deprecated firmware paths remain in scope for years, and attackers are patient. Practitioners should map every active device against the full Coinkite firmware history, not just the latest advisory, and retire any unit that cannot move past the affected lineage.

Trust Wallet Drops 25 Networks on September 15

Trust Wallet confirmed it will sunset 25 networks on September 15, narrowing the chain surface its users can transact on. For developers embedding the wallet, the cut means removing RPC endpoints, token lists, and signing paths tied to the dropped networks before that date, and warning end users whose only path to a chain was through Trust Wallet. Custody teams should audit which sub-wallets still depend on those chains so a sunset does not strand assets behind an unsupported signer.

What Practitioners Should Check This Week

Three concrete checks follow from the evidence. First, any Coldcard on affected firmware must have its seeds re-generated on verified hardware and its multisig signer set reissued before the next signing window. Second, replay the March 2021 firmware lineage against every device still in inventory, because the $38 million drain shows that old bugs keep paying out. Third, finish the Trust Wallet migration before September 15 so deprecated networks do not break a production wallet flow on the day they go dark.