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.
core.trac.wordpress.org/changeset/45997
github.com/WordPress/WordPress/commit/30ac67579559fe42251b5a9f887211bf61a8ed68
lists.debian.org/debian-lts-announce/2019/10/msg00023.html
seclists.org/bugtraq/2020/Jan/8
wordpress.org/news/2019/09/wordpress-5-2-3-security-and-maintenance-release/
wpvulndb.com/vulnerabilities/9867
www.debian.org/security/2020/dsa-4599
www.debian.org/security/2020/dsa-4677