about the problem.
In a statement, Michael Briggs, a spokesman for the Sanders campaign told the Guardian the issue was the result of systemic failures by NGP-VAN. Sadly, the vendor who runs the DNCs voter file program continues to make serious errors, said Briggs. On more than one occasion, the vendor has dropped the firewall between the data of different Democratic campaigns. Our campaign months ago alerted the DNC to the fact that campaign data was being made available to other campaigns. At that time our campaign did not run to the media, relying instead on assurances from the vendor.
He added of Wednesdays incident: Unfortunately, yesterday, the vendor once again dropped the firewall between the campaigns for some data. After discussion with the DNC it became clear that one of our staffers accessed some modeling data from another campaign. That behavior is unacceptable and that staffer was immediately fired. We are as interested as anyone in making sure that the software flaws are corrected since mistakes by the DNCs vendor also have made our records vulnerable. We are working with the DNC and the vendor and hope that this kind of lapse will not occur again.
http://www.theguardian.com/us-news/2015/dec/18/democrats-punish-bernie-sanders-campaign-following-clinton-data-breach