The MITRE CVE dictionary describes this issue as:
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.
Find out more about CVE-2018-16844 from the
MITRE CVE dictionary dictionary and
This issue did not affect the versions of rh-nginx18-nginx as shipped with Red Hat Software Collections as they did not include the vulnerable module ngx_http_v2_module.