Attacker Mints 46B Fake BTC After Exploiting Dual Bugs on Symbiosis

TL;DR:
- The attacker generated approximately 46.1 billion synthetic syBTC tokens from an initial deposit of 330 satoshis ($0.25) on September 11, 2026.
- Preliminary losses confirmed by the protocol stood at 9.97 BTC (around $770,000), of which the attacker liquidated 4.39 WBTC for about $336,000 on Uniswap.
- The Symbiosis team secured 15 BTC in a multisig wallet and kept the native Bitcoin bridge paused to submit the code to an external audit.
Last Friday, cross-chain protocol Symbiosis fell victim to a cyberattack caused by two vulnerabilities that allowed the creation of billions of unbacked synthetic assets.
- Symbiosis (@symbiosis_fi) September 14, 2026
An attacker deposited 330 satoshis (the smallest unit of Bitcoin, valued at around $0.25 at the time) to execute 12 irregular transactions across BNB Chain, Ethereum, and Rootstock in just 4 minutes. The malicious operation culminated in the issuance of 46.1 billion syBTC, a synthetic token designed to track real Bitcoin deposits on a 1:1 basis within the protocol. This notional volume exceeded the historical 21 million coin cap of the Bitcoin network by more than 2,000 times.
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