A March 2021 firmware integration error in Coldcard hardware wallets routed seed generation to a deterministic software pseudorandom number generator (PRNG) — MicroPython's Yasmarang fallback — instead of the STM32 hardware random number generator (RNG). The root cause was in Coldcard's production config: the macro MICROPY_HW_ENABLE_RNG was set to zero because Coinkite supplies its own hardware-RNG wrapper, but the libngu library checked whether the macro existed rather than whether it was enabled. As a result, the MicroPython PRNG fallback was used, initialized only from the chip's unique ID (UID) and timer registers, with no fresh entropy collected after initialization. An attacker who can determine or sufficiently constrain the device UID, timer state, and prior RNG-call history can reproduce candidate output streams offline without accessing the device. Candidate seeds can be checked by deriving their addresses and comparing them with public blockchain data. Effective entropy is estimated at roughly 40 bits on Mk3 and about 72 bits on Mk4/Mk5/Q, far below the 128 bits expected for a 12-word BIP-39 seed. On July 30, an attacker drained 1,196 Bitcoin addresses in 41 minutes, stealing 1,082.65 BTC (~$70.2 million). Galaxy Research identified the sweep by a unique on-chain signature pattern: 30 sat/vB fee rate with no change output, not seen in any other Bitcoin transactions in the prior 30 days. A related but separate weak-PRNG vulnerability dubbed 'Ill Bloom' (researched by Coinspect) affected older software wallets across Bitcoin, Ethereum, Tron, Rootstock, and Polygon, draining over $5 million since May.