CVE 2013-3567
Puppet 2.7.x before 2.7.22 and 3.2.x before 3.2.2, and Puppet Enterprise before 2.8.2, deserializes untrusted YAML, which allows remote attackers to instantiate arbitrary Ruby classes and execute arbitrary code via a crafted REST API call.
See the 
CVE page on Mitre.org
for more details.
