Major non-fungible token marketplace OpenSea has confirmed being hit by a widespread data breach that resulted in the exposure of users' and newsletter subscribers' email addresses, TechCrunch reports. OpenSea noted that the breach has stemmed from credential misuse by an employee at its email vendor Customer.io. "If you have shared your email with OpenSea in the past, you should assume you were impacted," said OpenSea, which reiterated ongoing investigation with Customer.io regarding the incident that has already been reported to law enforcement. Meanwhile, Customer.io emphasized that no other client data is believed to have been compromised in the incident. "The employee in question has had all access removed and has been suspended pending the conclusion of our investigation," a Customer.io spokesperson said. OpenSea's email breach comes amid increasing cyberattacks aimed at cryptocurrency startups. BlockFi, Circle, and other cryptocurrency firms have been impacted by a data breach at HubSpot in March, while $625 million have been stolen from the hack of the Ronin blockchain network.