It was found that lxc-user-nic could potentially have been tricked into operating on a network namespace over which the caller did not hold privilege.
Created lxc tracking bugs for this issue:
Affects: epel-6 [bug 1431559]
Affects: epel-7 [bug 1431558]
lxc-1.0.10-2.el6 has been pushed to the Fedora EPEL 6 stable repository. If problems still persist, please make note of it in this bug report.
lxc-1.0.10-2.el7 has been pushed to the Fedora EPEL 7 stable repository. If problems still persist, please make note of it in this bug report.