A 5-year-old bug just drained $38 million in BTC from 500 wallets.

Friday, July 31, 2026

As July ends, the options market is flashing a clear bearish signal heading into August. The $60,000 bitcoin put option — a position protecting against a price drop — is now the most popular bet on Deribit, the world’s largest crypto options exchange, with notional open interest of $1.17 billion. Until yesterday, $70,000 and $72,000 call options were the market leaders, each boasting $2.5 billion in open interest as traders positioned for a post-Fed rally. That didn’t happen, and Friday’s $10 billion options expiry at 08:00 UTC likely flushed much of that bullish positioning. Seasonality adds to the caution: since 2013, a positive July — bitcoin is up 8.9% this month, near the historical median of 8.61% — has typically been followed by a negative August, with a median return of −7.51%. BTC and ETH are falling today even as equities rally, with the CoinDesk 20 on track for its best monthly gain since July 2025. Stay alert.

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Market snapshot

As of 9am EST

Asset

Price

24h

BTC

$63,756.89

+0.06%

ETH

$1,882.11

−1.04%

SOL

$73.45

−1.44%

XRP

$1.07

−1.77%

Prices approximate. Visit coindesk.com/price for live data.

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Major bitcoin wallet flaw drains 594 BTC in 25-minute sweep.

Roughly 594 bitcoin — worth approximately $38 million — was swept from around 500 separate wallets between 01:31 and 01:56 UTC on Friday in an attack traced to a flaw in how Coldcard hardware wallets generated their cryptographic keys. The attacker moved 1,324 chunks of bitcoin across 500 transactions inside a three-block window, then consolidated 562 BTC into a single address that has not moved. Every drained wallet was single-signature and held more than 0.15 BTC, with many dormant for years. The vulnerability was introduced in Coldcard firmware 4.0.0 in March 2021: a build setting caused devices to skip their hardware randomness generator and fall back to a software substitute seeded from the chip’s serial number and clock registers — none of which are secrets. Block’s Bitcoin engineering team disclosed the flaw publicly because exploitation was already under way. Coinkite has warned users who created seeds on Mk3 devices running firmware 4.0.1 or later, and stated that Mk4, Q, and Mk5 appear unaffected. The exposure extends beyond wallet seeds to paper wallet private keys, seed-splitting masks, device cloning keys, and Key Teleport transfers. Bitcoin traded above $63,700 as the news broke, with the drain appearing to have little immediate market impact.

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