Munin::Master::Node in Munin before 2.0.18 allows remote attackers to cause a denial of service (abort data collection for node) via a plugin that uses "multigraph" as a multigraph service name.
https://github.com/munin-monitoring/munin/blob/2.0.18/ChangeLog
http://www.ubuntu.com/usn/USN-2090-1