The following flaw was found in Jenkins:
Access to the /jnlpJars/ URL was not limited to the specific JAR files users needed to access, allowing browsing directories and downloading other files in the Jenkins servlet resources, such as web.xml.
The information gained is very limited, and it requires a specific setup to gain any non-public information this way.
External References:
https://wiki.jenkins-ci.org/display/SECURITY/Jenkins+Security+Advisory+2015-11-11