An attacker exploited two software flaws in Symbiosis’ Bitcoin Bridge on September 11, beginning with a deposit of 330 satoshi, worth about 25 cents, and creating approximately 46.1 billion syBTC. The attacker processed 12 bogus deposits across BNB Chain, Ethereum and Rootstock in about four minutes. Symbiosis said the bridge misread the sender information in Bitcoin transactions, allowing the attacker to appear as both an approved depositor and bridge administrator. That access enabled a negative minimum fee, while a second bug added the negative fee to deposits instead of subtracting it, allowing arbitrary deposit values. The attacker extracted value from available Bitcoin-linked liquidity, including approximately 4.39 WBTC liquidated through Uniswap v4 for roughly $336,000. Symbiosis’ preliminary estimate puts total losses to liquidity providers and affected users at 9.97 BTC, or about $770,000. The project halted its native Bitcoin Bridge, plans to use some Bitcoin evacuated during the attack and separate compensation arrangements to cover losses, and is rewriting and independently auditing the Bitcoin-side software.