Winlogbeat versions before 5.6.16 and 6.6.2 had an insufficient logging flaw. An attacker able to inject certain characters into a log entry could prevent Winlogbeat from recording the event.
Source: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2019-7613
Reference (s):
- https://discuss.elastic.co/t/elastic-stack-6-6-2-and-5-6-16-security-update/173180
- https://www.elastic.co/community/security