Insufficient sanitization of the query parameter in templates/html/search_opensearch.php could lead to reflected cross-site scripting or iframe injection.
https://usn.ubuntu.com/4002-1/
https://lists.debian.org/debian-lts-announce/2019/05/msg00046.html
https://github.com/doxygen/doxygen/commit/1cc1adad2de03a0f013881b8960daf89aa155081
https://bugzilla.gnome.org/show_bug.cgi?id=762934
http://www.securityfocus.com/bid/108476
http://lists.opensuse.org/opensuse-security-announce/2019-06/msg00000.html