The MITRE CVE dictionary describes this issue as:
In Apache httpd 2.4.0 to 2.4.29, the expression specified in <FilesMatch> could match '$' to a newline character in a malicious filename, rather than matching only the end of the filename. This could be exploited in environments where uploads of some files are are externally blocked, but only by matching the trailing portion of the filename.
Find out more about CVE-2017-15715 from the
MITRE CVE dictionary dictionary and
The "FilesMatch" directive is not enabled in the default httpd configuration as shipped with Red Hat Enterprise Linux, and needs to be explicitly enabled. Therefore this flaw has no impact on the default versions of the httpd package as shipped with Red Hat Enterprise Linux.