Jenkins before 1.586 does not set the secure flag on session cookies when run on Tomcat 7.0.41 or later, which makes it easier for remote attackers to capture cookies by intercepting their transmission within an HTTP session.
https://jenkins.io/changelog-old/
https://issues.jenkins-ci.org/browse/JENKINS-25019
https://github.com/jenkinsci/jenkins/commit/582128b9ac179a788d43c1478be8a5224dc19710
https://bugzilla.redhat.com/show_bug.cgi?id=1185148
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=769682