We have released Puppet agent 1.10.1.
In versions prior to Puppet agent 1.10.1, an authenticated agent could make a catalog request with facts encoded in YAML. The Puppet master did not properly validate and reject the request, resulting in the server loading arbitrary objects, which could lead to remote code execution. You should update to the latest version to resolve this security issue.
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Jorie Tappa
Technical Writer @ Puppet