is_blog_installed in wp-includes/functions.php in WordPress before 5.5.2 improperly determines whether WordPress is already installed, which might allow an attacker to perform a new installation, leading to remote code execution (as well as a denial of service for the old installation).
https://www.debian.org/security/2020/dsa-4784
https://wpscan.com/vulnerability/10450
https://wordpress.org/news/2020/10/wordpress-5-5-2-security-and-maintenance-release/
https://lists.debian.org/debian-lts-announce/2020/11/msg00004.html
https://github.com/WordPress/wordpress-develop/commit/2ca15d1e5ce70493c5c0c096ca0c76503d6da07c