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.
Kibana versions before 5.6.15 and 6.6.1 contain an arbitrary code execution flaw in the security audit logger. If a Kibana instance has the setting xpack.security.audit.enabled set to true, an attacker could send a request that will attempt to execute javascript code. This could possibly lead to an attacker executing arbitrary commands with permissions of the Kibana process on the host system.
References:
https://discuss.elastic.co/t/elastic-stack-6-6-1-and-5-6-15-security-update/169077
Kibana versions before 5.6.15 and 6.6.1 had a cross-site scripting (XSS) vulnerability that could allow an attacker to obtain sensitive information from or perform destructive actions on behalf of other Kibana users.
The Kibana fix for CVE-2017-8451 was found to be incomplete. With X-Pack installed, Kibana versions before 6.0.1 and 5.6.5 have an open redirect vulnerability on the login page that would enable an attacker to craft a link that redirects to an arbitrary website.
Kibana versions prior to 6.0.1 and 5.6.5 had a cross-site scripting (XSS) vulnerability via URL fields that could allow an attacker to obtain sensitive information from or perform destructive actions on behalf of other Kibana users.
Kibana versions 4.0 to 4.6, 5.0 to 5.6.12, and 6.0 to 6.4.2 contain an error in the way authorization credentials are used when generating PDF reports. If a report requests external resources plaintext credentials are included in the HTTP request that could be recovered by an external resource provider.
Kibana versions before 6.4.3 and 5.6.13 contain an arbitrary file inclusion flaw in the Console plugin. An attacker with access to the Kibana Console API could send a request that will attempt to execute javascript code. This could possibly lead to an attacker executing arbitrary commands with permissions of the Kibana process on the host system.
In Elasticsearch versions 6.0.0-beta1 to 6.2.4 a disclosure flaw was found in the snapshot API. When the accesskey and securitykey parameters are set using the snapshot API they can be exposed as plain text by users able to query the snapshot API.
Kibana versions after 5.1.1 and before 5.6.7 and 6.1.3 had a cross-site scripting (XSS) vulnerability in the tag cloud visualization that could allow an attacker to obtain sensitive information from or perform destructive actions on behalf of other Kibana users.
The fix in Kibana for ESA-2017-23 was incomplete. With X-Pack security enabled, Kibana versions before 6.1.3 and 5.6.7 have an open redirect vulnerability on the login page that would enable an attacker to craft a link that redirects to an arbitrary website.