Hackers post what appear to be login credentials for more than 453,000 Yahoo accounts. Hackers say they retrieved the credentials in plaintext from an unidentified service on Yahoo. Yahoo confirmed a breach that hit the site’s Contributor Network (previously Associated Content) The breach was contained in an “older file,” and only about 5 percent of the exposed credentials were still valid on Yahoo.com. Yahoo: “We are fixing the vulnerability that led to the disclosure of this data, changing the passwords of affected Yahoo! users””]
Source: https://arstechnica.com/information-technology/2012/07/yahoo-service-hacked/