In affected versions of WordPress, some private posts, which were previously public, can result in unauthenticated disclosure under a specific set of conditions. This has been patched in version 5.4.1, along with all the previously affected versions via a minor release (5.3.3, 5.2.6, 5.1.5, 5.0.9, 4.9.14, 4.8.13, 4.7.17, 4.6.18, 4.5.21, 4.4.22, 4.3.23, 4.2.27, 4.1.30, 4.0.30, 3.9.31, 3.8.33, 3.7.33).
https://www.debian.org/security/2020/dsa-4677
https://wordpress.org/support/wordpress-version/version-5-4-1/#security-updates
https://lists.debian.org/debian-lts-announce/2020/05/msg00011.html
https://github.com/WordPress/wordpress-develop/security/advisories/GHSA-xhx9-759f-6p2w