A flaw was found in PolicyKit (aka polkit) 0.115 that allows a user with a uid greater than INT_MAX to successfully execute any systemctl command.
https://www.debian.org/security/2018/dsa-4350
https://usn.ubuntu.com/3861-2/
https://usn.ubuntu.com/3861-1/
https://security.gentoo.org/glsa/201908-14
https://lists.debian.org/debian-lts-announce/2019/01/msg00021.html
https://gitlab.freedesktop.org/polkit/polkit/issues/74
https://bugs.debian.org/915332