Symbiosis recovers 15 BTC after Bitcoin Bridge exploit, offers attacker 20% bounty

A cross-chain protocol walking away from a $46.1 billion notional exploit with roughly $336,000 in actual losses sounds like a near-miss story with a strange silver lining. That is roughly the situation Symbiosis found itself navigating after an attacker hit its native Bitcoin Bridge on September 11, 2026. The breach, discovered at approximately 04:28 UTC, exploited a vulnerability in Symbiosis’s BridgeV2 contract. The flaw let the attacker mint an almost incomprehensibly large quantity of unbacked syBTC tokens, approximately 2^62 raw units, a figure whose notional face value clocked in around $46.1 billion. The actual damage, however, was far more contained: the attacker converted roughly 4.39 WBTC on Ethereum’s Uniswap V4, walking away with about $336,000 in real money. What actually happened Blockaid, an on-chain security firm, identified the suspicious activity before Symbiosis made any public announcement, which helped compress the window for further extraction. Symbiosis responded by halting all BTC-related routing across the protocol. The team confirmed that other cross-chain routes remained fully operational. The native Bitcoin Bridge stayed dark as of September 13, with no...