The Committee on Oversight and Government Reform said today that Marilyn Tavenner, the Centers for Medicare and Medicaid Services head who has presided over’s troubled first year, must testify later this month.

 The Committee is looking for answers as news breaks today that hackers successfully accessed a server, with the attack remaining undetected for several weeks. The federal government says no information was compromised in the attack.

The news release also notes that “security documents produced by one of’s contractors, MITRE, showed that [the Department of Health and Human Services] downplayed vulnerabilities prior to launch.”

News of the successful hack follows the HHS’s controversial admission last month that Tavenner may have deleted correspondence, even though as the head of CMS, she’s ultimately in charge of maintaining agency records.

Also in August, the House Energy and Commerce Committee released correspondence in which Tavenner instructs a subordinate to delete an e-mail correspondence with the White House about

In a news release issued this evening, Oversight and Government Reform Committee chairman Darrell Issa said:

Considering this Administration launched over the objections of CMS, it’s unsurprising that the website has suffered a “malicious attack.” For nearly a year, the Administration has dismissed concerns about the security of, even as it obstructed Congressional oversight of the issue. The Committee will continue to push for answers from the Administration and Administrator Tavenner must testify on the subject of transparency, accountability, and information security alongside the Government Accountability Office at our September 18th hearing. Additionally, just last month, the Administration admitted that Tavenner, who was the senior official responsible for the disastrous rollout, experienced a similar email “loss” as IRS official Lois Lerner.

— Jillian Kay Melchior is a Thomas L. Rhodes Fellow for the Franklin Center for Government and Public Integrity. She is also a Senior Fellow at the Independent Women’s Forum.