In WordPress before 4.9.9 and 5.x before 5.0.1, when the Apache HTTP Server is used, authors could upload crafted files that bypass intended MIME type restrictions, leading to XSS, as demonstrated by a .jpg file without JPEG data.
www.securityfocus.com/bid/106220
codex.wordpress.org/Version_4.9.9
github.com/WordPress/WordPress/commit/246a70bdbfac3bd45ff71c7941deef1bb206b19a
lists.debian.org/debian-lts-announce/2019/02/msg00019.html
wordpress.org/news/2018/12/wordpress-5-0-1-security-release/
wordpress.org/support/wordpress-version/version-5-0-1/
wpvulndb.com/vulnerabilities/9175
www.debian.org/security/2019/dsa-4401
www.zdnet.com/article/wordpress-plugs-bug-that-led-to-google-indexing-some-user-passwords/