Not really Yahoo
On July 11, Yahoo! learned that email addresses and passwords associated with Yahoo! Contributor Network
were published online by a hacker group.
Yahoo! recently confirmed that an older file containing approximately 450,000 email addresses and passwords was compromised. The compromised information was provided by writers who had joined Associated Content prior to May 2010, when it was acquired by Yahoo!. (Associated Content is now the Yahoo! Contributor Network.) This compromised file was a standalone file that was not used to grant access to Yahoo! systems and services.
We have taken swift action and have now fixed this vulnerability
, deployed additional security measures for affected Yahoo! users
, enhanced our underlying security controls
and are in the process of notifying affected users
. In addition, we will continue to take significant measures to protect our users and their data.
If you joined Associated Content prior to May 2010 using your Yahoo! email address, please log in to your Yahoo! account where you may be prompted to answer a series of authentication questions to change and validate your credentials.
At Yahoo! we take security very seriously and invest heavily in protective measures to ensure the security of our users and their data across all our products.
We sincerely apologize to all affected users. http://ycorpblog.com/2012/07/13/yahoo-0713201/