A March 2021 firmware change had routed seed generation through a software random-number generator seeded from public constants rather than the device's hardware source, so the affected seeds could be recomputed by anyone who found the flaw. The secure element protected the keys as designed; it could not protect seeds that were weak before they reached it.
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Weak seeds drain Coldcard hardware wallets
An attacker swept about 1,816 BTC from more than 5,200 addresses whose seeds had been generated with predictable randomness.
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IN THE SHOWBroken Trust