Before WordPress 4.9.5, the version string was not escaped in the get_the_generator function, and could lead to XSS in a generator tag.
www.securityfocus.com/bid/103775
www.securitytracker.com/id/1040836
codex.wordpress.org/Version_4.9.5
core.trac.wordpress.org/changeset/42893
github.com/WordPress/WordPress/commit/31a4369366d6b8ce30045d4c838de2412c77850d
lists.debian.org/debian-lts-announce/2018/04/msg00031.html
wordpress.org/news/2018/04/wordpress-4-9-5-security-and-maintenance-release/
wpvulndb.com/vulnerabilities/9055
www.debian.org/security/2018/dsa-4193