wordpress is vulnerable to cache poisoning. The vulnerability exists due to the lack of the Vary: Origin header in certain requests.
blog.wpscan.org/wordpress/security/release/2019/10/15/wordpress-524-security-release-breakdown.html
core.trac.wordpress.org/changeset/46478
github.com/WordPress/WordPress/commit/b224c251adfa16a5f84074a3c0886270c9df38de
seclists.org/bugtraq/2020/Jan/8
wordpress.org/news/2019/10/wordpress-5-2-4-security-release/
wpvulndb.com/vulnerabilities/9911
www.debian.org/security/2020/dsa-4599
www.debian.org/security/2020/dsa-4677