WordPress before 5.1.1 does not properly filter comment content, leading to Remote Code Execution by unauthenticated users in a default configuration. This occurs because CSRF protection is mishandled, and because Search Engine Optimization of A elements is performed incorrectly, leading to XSS. The XSS results in administrative access, which allows arbitrary changes to .php files. This is related to wp-admin/includes/ajax-actions.php and wp-includes/comment.php.
www.securityfocus.com/bid/107411
blog.ripstech.com/2019/wordpress-csrf-to-rce/
github.com/WordPress/WordPress/commit/0292de60ec78c5a44956765189403654fe4d080b
lists.debian.org/debian-lts-announce/2019/03/msg00044.html
wordpress.org/news/2019/03/wordpress-5-1-1-security-and-maintenance-release/
wordpress.org/support/wordpress-version/version-5-1-1/
wpvulndb.com/vulnerabilities/9230
www.debian.org/security/2020/dsa-4677