NGINX before 1.17.7, with certain error_page configurations, allows HTTP request smuggling, as demonstrated by the ability of an attacker to read unauthorized web pages in environments where NGINX is being fronted by a load balancer.
lists.opensuse.org/opensuse-security-announce/2020-02/msg00013.html
nginx.org/en/CHANGES
seclists.org/fulldisclosure/2021/Sep/36
bertjwregeer.keybase.pub/2019-12-10%20-%20error_page%20request%20smuggling.pdf
duo.com/docs/dng-notes#version-1.5.4-january-2020
github.com/kubernetes/ingress-nginx/pull/4859
github.com/nginx/nginx/commit/c1be55f97211d38b69ac0c2027e6812ab8b1b94e
security.netapp.com/advisory/ntap-20200127-0003/
support.apple.com/kb/HT212818
usn.ubuntu.com/4235-1/
usn.ubuntu.com/4235-2/