Good news: Outgoing Secretary of State Hillary Clinton, after being sidelined for weeks by a concussion and blood clot, returned to work Monday. More good news: Now that she’s feeling better, she will soon testify before Congress about the Sept. 11 terror attack that killed four Americans, including Ambassador Christopher Stevens, at the U.S. Consulate in Benghazi, Libya.

And in the wake of a withering report by the outgoing Senate Homeland Security and Government Affairs Committee, Secretary Clinton should face some tough questions about Benghazi from federal lawmakers. Sen. Bob Corker, R-Tenn., told MSNBC Tuesday that she is expected to appear before the Senate Foreign Relations Committee on Jan. 22.

The Senate Homeland Security Committee report, issued on Dec. 30, cites “extremely poor security in a threat environment that was ‘flashing red.’ ” It faults the State Department for “ignoring repeated appeals from U.S. staff in Benghazi for more security resources.”

The report also criticizes the Obama administration for being “inconsistent” in its versions of what went so horribly wrong in Benghazi:

“If the fact that Benghazi was indeed a terrorist attack had been made clear from the outset by the administration, there would have been much less confusion about what happened in Benghazi that terrible night.”

Sen. Lindsey Graham, R-S.C., released a statement Tuesday insisting that “the stonewalling on Benghazi by the Obama administration must come to an end.” He warned that unless the administration is more forthcoming, he will put a senatorial hold on the confirmation of John Brennan, the president’s nominee for CIA director.

White House spokesman Jay Carney said Tuesday that “it would be unfortunate” if Mr. Brennan’s confirmation were held up due to the “highly politicized” issue of Benghazi.

That’s true. Sen. Graham himself has said Mr. Brennan, who has an impressive record in the intelligence service and has been President Barack Obama’s chief counterterrorism adviser, seems well qualified for the crucial task of running the CIA.

But it’s also unfortunate that nearly four months after the Benghazi outrage, crucial questions remain unanswered.

Joe Lieberman, “independent Democrat” from Connecticut, was chairman of the Senate Homeland Security Committee that issued the scathing Benghazi report. He retired from the Senate last week after four terms.

But before his departure, he and Maine Sen. Susan Collins, ranking Republican on the Homeland Security Committee, co-wrote an op-ed that painted a shocking picture of high-level negligence.

As Sens. Lieberman and Collins reported:

“The terrorists essentially walked into the compound unimpeded and set it ablaze because of the extremely poor security. This stark reality shaped our investigation as we sought to understand how each layer of security typical at diplomatic posts around the world broke down so completely and quickly in Benghazi. We believe the closed-circuit television video of the attack, which shows this failure in real time, should be released to the public, because it will make clear how unprepared the State Department was for this attack.”

And we believe Secretary Clinton — and John Kerry, nominated by the president to succeed her — should make clear what overdue steps are being taken to prevent another Benghazi.