The change_user method in the SUIDManager (lib/puppet/util/suidmanager.rb) in Puppet 2.6.x before 2.6.14 and 2.7.x before 2.7.11, and Puppet Enterprise (PE) Users 1.0, 1.1, 1.2.x, 2.0.x before 2.0.3 does not properly manage group privileges, which allows local users to gain privileges via vectors related to (1) the change_user not dropping supplementary groups in certain conditions, (2) changes to the eguid without associated changes to the egid, or (3) the addition of the real gid to supplementary groups.