The MITRE CVE dictionary describes this issue as:
When parsing the AIA-Extension field of a client certificate, Apache Tomcat Native Connector 1.2.0 to 1.2.14 and 1.1.23 to 1.1.34 did not correctly handle fields longer than 127 bytes. The result of the parsing error was to skip the OCSP check. It was therefore possible for client certificates that should have been rejected (if the OCSP check had been made) to be accepted. Users not using OCSP checks are not affected by this vulnerability.
Find out more about CVE-2017-15698 from the
MITRE CVE dictionary dictionary and