In Couchbase Server 6.0.0 and 5.5.0, the eventing service exposes system diagnostic profile via an HTTP endpoint that does not require credentials on a port earmarked for internal traffic only. This has been remedied in version 6.0.1 and now requires valid credentials to access.
An issue was discovered in Couchbase Server 5.5.x through 5.5.3 and 6.0.0. The Memcached "connections" stat block command emits a non-redacted username. The system information submitted to Couchbase as part of a bug report included the usernames for all users currently logged into the system even if the log was redacted for privacy. This has been fixed (in 5.5.4 and 6.0.1) so that usernames are tagged properly in the logs and are hashed out when the logs are redacted.
In Couchbase Server 6.0, credentials cached by a browser can be used to perform a CSRF attack if an administrator has used their browser to check the results of a REST API request.
Couchbase Server 6.5.x, 6.6.0 through 6.6.2, and 7.0.0, has a Buffer Overflow. A specially crafted network packet sent from an attacker can crash memcached.
An issue was discovered in Couchbase Server 6.x through 6.6.1. The Couchbase Server UI is insecurely logging session cookies in the logs. This allows for the impersonation of a user if the log files are obtained by an attacker before a session cookie expires.