Ankr's cross-chain bridge has suffered a security breach, resulting in the theft of approximately $304,500 in crypto assets, according to estimates from SlowMist. The hacker exploited a previously processed transaction on the Optimism network to generate five counterfeit transfer confirmations, altering the recipients, tokens, and amounts involved. Each of these fake confirmations included valid signatures from trusted participants of the bridge, enabling the attacker to bypass verification and withdraw funds via the Ethereum blockchain. The source of these signatures has yet to be identified.