WordPress before 5.2.4 has a Server Side Request Forgery (SSRF) vulnerability because Windows paths are mishandled during certain validation of relative URLs.
WordPress before 5.2.3 has an issue with URL sanitization in wp_kses_bad_protocol_once in wp-includes/kses.php that can lead to cross-site scripting (XSS) attacks.
In WordPress before 5.2.3, validation and sanitization of a URL in wp_validate_redirect in wp-includes/pluggable.php could lead to an open redirect if a provided URL path does not start with a forward slash.
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.