Elasticsearch Logstash 1.0.14 through 1.4.x before 1.4.2 allows remote attackers to execute arbitrary commands via a crafted event in (1) zabbix.rb or (2) nagios_nsca.rb in outputs/.
https://www.elastic.co/community/security/
http://www.securityfocus.com/archive/1/532841/100/0/threaded