This indicates an attack attempt to exploit a Remote Code Execution Vulnerability in Exim.
A remote, unauthenticated attacker can exploit this vulnerability by sending a handshake message with a crafted SNI to an Exim server that is configured to accept TLS connections. Successful exploitation will lead to the attacker being able to execute arbitrary code with the privileges of the root user.
Exim Project Exim before 4.92.2
System Compromise: Remote attackers can gain control of vulnerable systems.
Apply the most recent upgrade or patch from the vendor.