The agency is mum on how many people are impacted.

The U.S. Customs and Border Protection (CPB) disclosed earlier today that hackers have breached a database of travelers photos and license plates, according to the Washington Post. The agency declined to say how many people might have had their images stolen from the subcontractor that held them.

The CPB processes nearly 400 million travelers at ports of entry annually. In light of the fact that the CPB has been building an extensive photo database as part of its growing facial-recognition program, the privacy implications of this breach for American citizens and visitors could be grave.