Versions of MCollective prior to 2.10.4 deserialized YAML from agents without calling safe_load, allowing the potential for arbitrary code execution on the server. The fix for this is to call YAML.safe_load on input. This has been tested in all Puppet-supplied MCollective plugins, but there is a chance that third-party plugins could rely on this insecure behavior.

The mcollective-sshkey-security plugin before 0.5.1 for Puppet uses a server-specified identifier as part of a path where a file is written. A compromised server could use this to write a file to an arbitrary location on the client with the filename appended with the string "_pub.pem".

On Windows installations of the mcollective-puppet-agent plugin, version 1.12.0, a non-administrator user can create an executable that will be executed with administrator privileges on the next "mco puppet" run. Puppet Enterprise users are not affected. This is resolved in mcollective-puppet-agent 1.12.1.

The mcollective-puppet-agent plugin before 1.11.1 for Puppet allows remote attackers to execute arbitrary code via vectors involving the --server argument.

The MCollective aes_security plugin, as used in Puppet Enterprise before 3.3.0 and Mcollective before 2.5.3, does not properly validate new server certificates based on the CA certificate, which allows local users to establish unauthorized Mcollective connections via unspecified vectors related to a race condition.