okular version 18.08 and earlier contains a Directory Traversal vulnerability in function "unpackDocumentArchive(...)" in "core/document.cpp" that can result in Arbitrary file creation on the user workstation. This attack appear to be exploitable via he victim must open a specially crafted Okular archive. This issue appears to have been corrected in version 18.08.1
https://www.debian.org/security/2018/dsa-4303
https://security.gentoo.org/glsa/201811-08
https://lists.debian.org/debian-lts-announce/2018/09/msg00027.html
https://cgit.kde.org/okular.git/commit/?id=8ff7abc14d41906ad978b6bc67e69693863b9d47