If you're a Yahoo Mail user, you might want to be on the lookout for a password reset notification. Yahoo has announced that it detected a "coordinated effort" to access some email accounts.
In a post to the company's official blog, Yahoo's Jay Rossiter explained that it did not appear that the attackers had breached Yahoo servers to collect information, but rather had logged in to a number of accounts using data collected from "a third party database."
That means that no one actually broke in to Yahoo servers — the attackers were likely using usernames and passwords that were stolen during some other leak of customer data, for example Adobe or LivingSocial.
Yahoo didn't say how many accounts were affected, but it is the second-largest webmail provider in the world, with well over a quarter of a billion accounts, so if it were only a few dozen accounts, it probably wouldn't receive this kind of attention from the security team.
Anyone affected should have received a text or email at a backup address saying their password has been reset. If you didn't have a secondary mode of notification attached to your Yahoo Mail account, try to log in — if your password works, you weren't affected (but should probably change it just in case). If it didn't, you should contact Yahoo and see about getting your access restored.
Devin Coldewey is a contributing writer for NBC News Digital. His personal website is coldewey.cc.