WordPress before 5.2.4 has a Server Side Request Forgery (SSRF) vulnerability because URL validation does not consider the interpretation of a name as a series of hex characters.
https://www.debian.org/security/2020/dsa-4677
https://www.debian.org/security/2020/dsa-4599
https://wpvulndb.com/vulnerabilities/9912
https://wordpress.org/news/2019/10/wordpress-5-2-4-security-release/
https://seclists.org/bugtraq/2020/Jan/8
https://lists.debian.org/debian-lts-announce/2019/11/msg00000.html
https://github.com/WordPress/WordPress/commit/608d39faed63ea212b6c6cdf9fe2bef92e2120ea