The Couchbase Sync Gateway 2.1.2 in combination with a Couchbase Server is affected by a previously undisclosed N1QL-injection vulnerability in the REST API. An attacker with access to the public REST API can insert additional N1QL statements through the parameters ?startkey? and ?endkey? of the ?_all_docs? endpoint.
Source: NIST
CVE-2019-9039