Exactly Protocol, a decentralized credit market on the Optimism network, has been targeted by a bridge exploit worth as much as $12 million.

The hacker used an exploiter contract on Ethereum that transferred deposits to Optimism before ultimately bridging stolen funds back to Ethereum, blockchain security firm De.Fi said in a tweet.

It is estimated that 7,160 ether (ETH) has been lost equating to $12.04 million at current prices.

The protocol's native governance token (EXA) slumped by more than 12% following the exploit as it currently trades at $5.51, per CoinMarketCap.

The hack coincides with a significant downturn across the wider cryptocurrency market, with several assets including XRP, LTC and BCH leading double-digit declines as roughly $1 billion in positions were liquidated in a a 24-hour period.

Cross-chain bridges have become a common attack vector for hackers due to the relatively novel technology. Last year it was estimated that over $2 billion was lost to bridge hacks, according to Chainalysis.