chef-server-api/app/controllers/users.rb in the API in Chef before 0.9.0 does not require administrative privileges for the create, destroy, and update methods, which allows remote authenticated users to manage user accounts via requests to the /users URI.

References

• https://nvd.nist.gov/vuln/detail/CVE-2010-5142
• chef/chef@c3bb41f
• http://tickets.opscode.com/browse/CHEF-1289
• https://github.com/rubysec/ruby-advisory-db/blob/master/gems/chef/CVE-2010-5142.yml