nginx before versions 1.15.6 and 1.14.1 has a vulnerability in the implementation of HTTP/2 that can allow for excessive CPU usage. This issue affects nginx compiled with the ngx_http_v2_module (not compiled by default) if the 'http2' option of the 'listen' directive is used in a configuration file.
https://www.debian.org/security/2018/dsa-4335
https://usn.ubuntu.com/3812-1/
https://support.apple.com/kb/HT212818
https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2018-16844
https://access.redhat.com/errata/RHSA-2018:3681
https://access.redhat.com/errata/RHSA-2018:3680
http://www.securitytracker.com/id/1042038
http://www.securityfocus.com/bid/105868
http://seclists.org/fulldisclosure/2021/Sep/36
http://mailman.nginx.org/pipermail/nginx-announce/2018/000220.html
http://lists.opensuse.org/opensuse-security-announce/2019-09/msg00035.html