Jenkins before versions 2.44, 2.32.2 is vulnerable to an information exposure in the internal API that allows access to item names that should not be visible (SECURITY-380). This only affects anonymous users (other users legitimately have access) that were able to get a list of items via an UnprotectedRootAction.
https://jenkins.io/security/advisory/2017-02-01/
https://github.com/jenkinsci/jenkins/commit/09cfbc9cd5c9df7c763bc976b7f5c51266b63719