In WordPress before 5.3.1, authenticated users with lower privileges (like contributors) can inject JavaScript code in the block editor, which is executed within the dashboard. It can lead to an admin opening the affected post in the editor leading to XSS.
github.com/WordPress/wordpress-develop/security/advisories/GHSA-pg4x-64rh-3c9v
hackerone.com/reports/731301
seclists.org/bugtraq/2020/Jan/8
wordpress.org/news/2019/12/wordpress-5-3-1-security-and-maintenance-release/
wpvulndb.com/vulnerabilities/9976
www.debian.org/security/2020/dsa-4599
www.debian.org/security/2020/dsa-4677