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.
https://puppetlabs.com/security/cve/cve-2013-3567/
http://www.ubuntu.com/usn/USN-1886-1
http://www.debian.org/security/2013/dsa-2715
http://secunia.com/advisories/54429
http://rhn.redhat.com/errata/RHSA-2013-1284.html
http://rhn.redhat.com/errata/RHSA-2013-1283.html
http://lists.opensuse.org/opensuse-security-announce/2013-08/msg00019.html
http://lists.opensuse.org/opensuse-security-announce/2013-08/msg00002.html