A flaw in Coldcard hardware wallet seed generation has been tied to the theft of roughly 714.8 Bitcoin from 192 victims, with the bulk of the losses occurring in 2021 and 2022. The exploit, first identified in March 2021, centered on weak entropy (randomness used to create wallet recovery phrases), a critical weakness because predictable seed phrases can allow attackers to reconstruct private keys and drain funds. The case highlights a core security assumption in self-custody: hardware wallets are only as secure as the randomness used when they generate wallet seeds.