CVE-2018-17188

Prior to CouchDB version 2.3.0, CouchDB allowed for runtime-configuration
of key components of the database. In some cases, this lead to
vulnerabilities where CouchDB admin users could access the underlying
operating system as the CouchDB user. Together with other vulnerabilities,
it allowed full system entry for unauthenticated users. Rather than waiting
for new vulnerabilities to be discovered, and fixing them as they come up,
the CouchDB development team decided to make changes to avoid this entire
class of vulnerabilities.