If you are using one of the 2 popular WordPress caching plugins (which you should!), please make sure you have updated them to their latest version.
Both W3 Total Cache and Super Cache have released an announcement regarding a major vulnerabilities in their software. Both plugin providers have fixed the exploit, however it requires you to update to the latest version if you are running either the W3 Total Cache or Super Cache WordPress plugin.
As WordPress gets more and more popular each day, it’s becoming a sugar coated candy for wannabe hackers. Therefore we also recommend using a security plugin (Our favorite is Better WP Security, if it works well on your setup) in addition to the caching plugins mentioned above.
Cheers!