An authentication bypass flaw has been found in PackageKit before 1.1.10 that allows users without administrator privileges to install signed packages. A local attacker can use this vulnerability to install vulnerable packages to further compromise a system.
https://www.debian.org/security/2018/dsa-4207
https://usn.ubuntu.com/3634-1/
https://bugzilla.redhat.com/show_bug.cgi?id=1565992