File CVE-2011-3872.msg of Package puppet.579

If you've set the 'certdnsnames' option in your master's
puppet.conf file, merely installing the updated packages is not
sufficient to fix this problem. You need to either pick a new DNS
name for the master and reconfigure all agents to use it or re-new
certificates on all agents.

Please refer to the documentation in
for detailed instructions and scripts.

Puppetlabs' site also provides more information: