Hackers targeted Clinton’s private mail server

While the attempts were apparently blocked by a “threat-monitoring” product that Clinton’s employees connected to her network in October 2013, there was a period of more than three months from June to October 2013 when that protection had not been installed, according to a letter from Ron Johnson, a republican senator from Wisconsin, chairman of the Homeland Security and Government Affairs Committee.
That means her server was possibly vulnerable to cyber attacks during that time.