Oracle Linux: CVE-2019-15718: ELSA-2019-3592: systemd security, bug fix, and enhancement update (MODERATE) (Multiple Advisories)

In systemd 240, bus_open_system_watch_bind_with_description in shared/bus-util.c (as used by systemd-resolved to connect to the system D-Bus instance), calls sd_bus_set_trusted, which disables access controls for incoming D-Bus messages. An unprivileged user can exploit this by executing D-Bus methods that should be restricted to privileged users, in order to change the system's DNS resolver settings.
An improper authorization flaw was discovered in systemd-resolved in the way it configures the exposed DBus interface org.freedesktop.resolve1. An unprivileged local attacker could call all DBus methods, even when marked as privileged operations. An attacker could abuse this flaw by changing the DNS, Search Domain, LLMNR, DNSSEC and other network link settings without any authorization, allowing control of the network names resolution process and cause the system to communicate with wrong or malicious servers.