A lot of famous blogs such as Mashable and Techcrunch speaking a bout wordpress security issues of older versions.this affects self hosted blogs not blogs hosted on wordpress.
wordpress official blog said:
Yesterday a vulnerability was discovered: a specially crafted URL could be requested that would allow an attacker to bypass a security check to verify a user requested a password reset. As a result, the first account without a key in the database (usually the admin account) would have its password reset and a new password would be emailed to the account owner. This doesn’t allow remote access, but it is very annoying.
We fixed this problem last night and have been testing the fixes and looking for other problems since then. Version 2.8.4 which fixes all known problems is now available for download and is highly recommended for all users of WordPress.
To prevent this attack download latest version of wordpress and upgrade.