An issue was discovered in Open Ticket Request System (OTRS) 6.0.x through 6.0.7. A carefully constructed email could be used to inject and execute arbitrary stylesheet or JavaScript code in a logged in customer's browser in the context of the OTRS customer panel application.
https://www.otrs.com/category/release-and-security-notes-en/
https://lists.otrs.org/pipermail/announce/2018/000720.html
https://lists.debian.org/debian-lts-announce/2019/08/msg00018.html
https://community.otrs.com/security-advisory-2018-02-security-update-for-otrs-framework/