Hackers are targeting millions of mail servers running vulnerable Exim mail transfer agent (MTA) versions, threat actors leverage the CVE-2019-10149 flaw. The flaw could be exploited by unauthenticated remote attackers to execute arbitrary commands on mail servers for some non-default server configurations. The issue resides in the deliver_message() function in /src/deliver.c and it is caused by the improper validation of recipient addresses. The issue could lead to remote code execution with root privileges on the mail server.”]
Source: https://securityaffairs.co/wordpress/87078/hacking/exim-servers-under-attacl.html