link_to_local_path in ebooks/conversion/plugins/html_input.py in calibre before 6.19.0 can, by default, add resources outside of the document root. https://github.com/0x1717/ssrf-via-img https://github.com/kovidgoyal/calibre/compare/v6.18.1...v6.19.0
Created calibre tracking bugs for this issue: Affects: fedora-all [bug 2245626]