Two critical and high severity security vulnerabilities in the highly popular “All in One” SEO WordPress plugin exposed over 3 million websites to takeover attacks.
The security flaws discovered and reported by Automattic security researcher Marc Montpas are a critical Authenticated Privilege Escalation bug (CVE-2021-25036) and a high severity Authenticated SQL Injection (CVE-2021-25037).
Over 800,000 vulnerable WordPress sites
The plugin’s developer released a security update to address both All in One bugs on December 7, 2021.
However, more than 820,000 sites using the plugin are yet to update their installation, according to download statistics for the last two weeks since the patch was released, and are still exposed to attacks.
What makes these flaws highly dangerous is that, even though successfully exploiting the two vulnerabilities requires threat actors to be authenticated, they only need low-level permissions such as Subscriber to abuse them in attacks.
Subscriber is a default WordPress user role (just as Contributor, Author, Editor, and Administrator), commonly enabled to allow registered users to comment on articles published on WordPress sites.
Although subscribers are typically only able to edit their own profile besides posting comments, in this case, they can exploit CVE-2021-25036 to elevate their privileges and gain remote code execution on vulnerable sites and, likely, completely take them over.