A flaw was found in the way Postgresql allowed a user to modify the behavior of a query for other users. An attacker with a user account could use this flaw to execute code with the permissions of superuser in the database. Versions 9.3 through 10 are affected.
https://www.postgresql.org/about/news/1834/
https://usn.ubuntu.com/3589-1/
https://bugzilla.redhat.com/show_bug.cgi?id=1547044
https://access.redhat.com/errata/RHSA-2018:3816
https://access.redhat.com/errata/RHSA-2018:2566