ZNC before 1.7.1-rc1 is prone to a path traversal flaw via ../ in a web skin name to access files outside of the intended skins directories.
https://www.debian.org/security/2018/dsa-4252
https://security.gentoo.org/glsa/201807-03
https://github.com/znc/znc/commit/a4a5aeeb17d32937d8c7d743dae9a4cc755ce773