A significant exploit had been identified in Exim. This exploit allows attackers to execute code as the root user on your server without authentication and was rated a 9.8 out of 10 in severity.
While Version 80 was never vulnerable to this exploit, and we released a patch for Version 78 last night, the recently End of Life Version 70 and Version 76 remained vulnerable. More details were released today, including information on exactly how to gain root access to a remote server.
Please refer this article for more details.
If you are using cPanel/WHM, please raise a ticket ASAP, and our team will help you to patch the exploit.