In macOS High Sierra before 10.13.5, an issue existed in CUPS. This issue was addressed with improved access restrictions.
https://www.debian.org/security/2018/dsa-4243
https://usn.ubuntu.com/3713-1/
https://support.apple.com/HT208849
https://security.gentoo.org/glsa/201908-08
https://lists.debian.org/debian-lts-announce/2018/07/msg00014.html