WordPress Security Team is sending out warning messages to thousands of wordpress users that their account has been compromised recently. Warning message include “We recently detected suspicious activity on your WordPress.com account. To protect your identity and keep your site safe, we’ve reset your password.” WordPress officially has not announce yet any security breach news on their website, but these warning mails are silently received by compromised account holders. Method of hack is still not confirmed, but hacking 15000 blogs from wordpress server and posting same article on all sites most obvious can’t be a client side hack.
Source: https://thehackernews.com/2012/10/15000-wordpress-blogs-hacked-for-making.html