In nspawn in systemd 233 through 259 before 260, an escape-to-host action can occur via a crafted optional config file.
In udev in systemd before 260, local root execution can occur via malicious hardware devices and unsanitized kernel output.
In systemd 258 before 260, a local unprivileged user can trigger an assert when a Delegate=yes and User=<unset> unit exists and is running.