Coldcard firmware flaw tied to $100M in stolen bitcoin
Security & Exploits ·
A years-old bug in Coldcard's code weakened the randomness used to generate wallet seeds, exposing holders to theft that attackers eventually exploited.
The flaw sat undetected in the hardware wallet's firmware for years before it was identified, according to Coindesk. Because the bug undermined the randomness underlying seed generation, wallets created under the flawed code produced keys that were more predictable than intended, giving attackers a path to reconstruct private keys rather than needing to compromise a device directly.
That distinction matters because Coldcard is a hardware wallet, a category typically marketed as a defense against remote theft. Crypto theft generally targets the keys or seed phrases that control funds rather than the coins themselves, and because blockchain settlement is final, once those keys are compromised the resulting transfers cannot be reversed. A weakness in the seed-generation process itself removes one of the main protections hardware wallets are meant to provide, since the vulnerability existed before a user ever exposed their device to an attacker.
The reported losses tied to the bug exceed $100M, according to the same Coindesk reporting, placing it among the larger disclosed losses linked to a single hardware-wallet defect. Corroborating coverage in the same cluster likewise describes a long-standing code vulnerability in the Coldcard wallet leading to $100M in compromised funds, indicating the figure and root cause are being reported consistently across at least two sources.
The episode fits a broader pattern in crypto theft in which the practical point of failure is control over private keys and seed material rather than the assets themselves, and where transparency on-chain aids tracing stolen funds after the fact but does nothing to prevent the initial compromise.
Not yet established is how many wallets were affected, over what exact time period the flawed code was in circulation, whether the vulnerability has since been patched, and what recovery options, if any, exist for holders whose funds were already stolen.