An error was found in the X-Pack Security TLS trust manager for versions 5.0.0 to 5.5.1. If reloading the trust material fails the trust manager will be replaced with an instance that trusts all certificates. This could allow any node using any certificate to join a cluster. The proper behavior in this instance is for the TLS trust manager to deny all certificates.

Logstash 1.4.x before 1.4.5 and 1.5.x before 1.5.4 with Lumberjack output or the Logstash forwarder does not validate SSL/TLS certificates from the Logstash server, which might allow attackers to obtain sensitive information via a man-in-the-middle attack.

The snapshot API in Elasticsearch before 1.6.0 when another application exists on the system that can read Lucene files and execute code from them, is accessible by the attacker, and the Java VM on which Elasticsearch is running can write to a location that the other application can read and execute from, allows remote authenticated users to write to and create arbitrary snapshot metadata files, and potentially execute arbitrary code.

Elasticsearch X-Pack Security versions 5.0.0 to 5.4.3, when enabled, can result in the Elasticsearch _nodes API leaking sensitive configuration information, such as the paths and passphrases of SSL keys that were configured as part of an authentication realm. This could allow an authenticated Elasticsearch user to improperly view these details.

In Kibana X-Pack security versions prior to 5.4.3 if a Kibana user opens a crafted Kibana URL the result could be a redirect to an improperly initialized Kibana login screen. If the user enters credentials on this screen, the credentials will appear in the URL bar. The credentials could then be viewed by untrusted parties or logged into the Kibana access logs.

Logstash 1.5.x before 1.5.3 and 1.4.x before 1.4.4 allows remote attackers to read communications between Logstash Forwarder agent and Logstash server.

Kibana before 4.5.4 and 4.1.11 when a custom output is configured for logging in, cookies and authorization headers could be written to the log files. This information could be used to hijack sessions of other users when using Kibana behind some form of authentication such as Shield.

Logstash prior to version 2.1.2, the CSV output can be attacked via engineered input that will create malicious formulas in the CSV data.

Logstash versions prior to 2.3.3, when using the Netflow Codec plugin, a remote attacker crafting malicious Netflow v5, Netflow v9 or IPFIX packets could perform a denial of service attack on the Logstash instance. The errors resulting from these crafted inputs are not handled by the codec and can cause the Logstash process to exit.

Kibana versions prior to 4.1.3 and 4.2.1 are vulnerable to a XSS attack.