In Couchbase Server 4.6.3 and 5.5.0, secondary indexing encodes the entries to be indexed using collatejson. When index entries contain certain characters like \t, <, >, it caused buffer overrun as encoded string would be much larger than accounted for, causing indexer service to crash and restart. This has been remedied in versions 5.1.2 and 5.5.2 to ensure buffer always grows as needed for any input.

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.

Some enterprises require that REST API endpoints include security-related headers in REST responses. Headers such as X-Frame-Options and X-Content-Type-Options are generally advisable, however some information security professionals additionally look for X-Permitted-Cross-Domain-Policies and X-XSS-Protection, which are more generally applicable to HTML endpoint, to be included too. These headers were not included in Couchbase Server 5.5.0 and 5.1.2 . They are now included in version 6.0.2 in responses from the Couchbase Server Views REST API (port 8092).

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.