This indicates an attack attempt to exploit a SQL injection vulnerability in SolusVM.
The vulnerability is due to the user input filters failing to properly sanitize the "deleteid" parameter value that is passed to "centralbackup.php". A remote attacker can exploit this to send a crafted query to execute SQL commands on a vulnerable server.
SolusVM before 1.13.07.
System Compromise: Remote attackers can add, view, delete or modify data in the database of the affected application
Apply the update from the vendor.