Symbiosis halts Bitcoin bridge after syBTC minting exploit

Symbiosis has halted its native Bitcoin bridge following a security exploit of its BridgeV2 contract. The attacker successfully minted a massive amount of unbacked synthetic BTC (syBTC) across the BNB Chain and Ethereum. While the minting involved billions in face value, the attacker managed to convert only a small portion into approximately 4.39 WBTC, realizing roughly $336,000 in real value.

The incident, identified by the cybersecurity platform Blockaid, occurred on September 11, 2026. Symbiosis confirmed that while BTC routing has been suspended to mitigate further risk, other routing protocols within the network remain operational and secure. The team reported recovering approximately 15 BTC and has offered a 20% bounty to the attacker.

This exploit follows recent vulnerabilities in other Bitcoin-related infrastructure, including the Liquid Network and Nomic, highlighting ongoing risks associated with cross-chain bridges and the transmission of authenticated messages between blockchains.