Yahoo said that the affected users have already been notified, though it's not clear how widespread the attack was. The company said it's working with federal law enforcement to find those responsible for the attempted breach. Because of that investigation, Yahoo said it could not comment beyond what it has publicly said in the blog post.
It's been a tough go recently for Yahoo Mail users. Last month, a small number of users on the service experienced a multiday outage, and, in some cases, users saw a backlog of email from up to two weeks.
The company was criticized during the outage for its public relations efforts during the incident. In this case, Yahoo apologized for the attempted attack right off the bat. "We regret this has happened and want to assure our users that we take the security of their data very seriously," the blog post said.