Websites that run WordPress and MailPoet, a plugin with more than 1.7 million downloads, are susceptible to hacks that give attackers almost complete control, researchers have warned.
"If you have this plugin activated on your website, the odds are not in your favor," Daniel Cid, CTO of security firm Sucuri, warned in a blog post published Tuesday. "An attacker can exploit this vulnerability without having any privileges/accounts on the target site. This is a major threat, it means every single website using it is vulnerable."
The bug allows attackers to remotely upload any file of their choice to vulnerable servers. Cid declined to provide specifics about the flaw other than to say it's the result of the mistaken assumption that WordPress admin_init hooks are called only when a user with administrator privileges visits a page inside the /wp-admin directory. In fact, "any call to /wp-admin/admin-post.php also executes this hook without requiring the user to be authenticated." The behavior makes it possible for anyone to upload files on vulnerable sites. The only safe version is the just released 2.6.7, which should be installed immediately on all vulnerable websites. MailPoet gives sites added abilities to create newsletters and automatically post notifications and responses.