BBC director general George Entwistle resigned at the weekend over the programme, which was aired on November 2 and led to former Tory Treasurer Lord McAlpine being wrongly linked to child abuse allegations.
Tim Davie, who is acting BBC director general while the corporation searches for Entwistle's replacement, has now vowed to "get a grip of the situation".
The summary of an internal investigation into the report by BBC Scotland director Ken MacQuarrie was released yesterday by the corporation, with the full text to be issued after disciplinary proceedings are completed.
MacQuarrie identified "unacceptable" failings regarding the Newsnight investigation, and said that basic journalistic checks were not completed.
He also noted that "there was a different understanding by the key parties about where the responsibility lay for the final editorial sign off for the story on the day".
A BBC spokesman later confirmed Johnston's involvement "in decisions about the BBC Newsnight report".
The Guardian's sources within the BBC claim that Liz Gibbons, Newsnight's acting editor, and Radio 5 Live's Adrian Van Klaveren, the supervising executive, could also face disciplinary action.
The BBC's director of news Helen Boaden and her deputy Steve Mitchell were not found to have had "anything at all to do with the failed Newsnight investigation into Lord McAlpine".
However they have 'stepped aside' from their roles pending an internal review into why a different Newsnight report on sex abuse claims against Jimmy Savile was dropped last year.
The BBC has said that once the review - overseen by former head of Sky News Nick Pollard - is concluded, Boaden and Mitchell "expect to then return to their positions".
In a statement after the MacQuarrie report summary was published, the BBC Trust said that there were clearly "serious failings in the normal checks and balances" in BBC journalism with regard to the November 2 Newsnight report.
"The measures that Tim Davie has put in place are sensible and appropriate while the inquiry carries out its work, and we note that consideration is being given to further action in respect of the November 2 Newsnight," The Trust said.
"We expect to receive regular updates on this issue from the acting director-general as he works with the utmost urgency to restore public confidence in the BBC and the integrity of its journalism."
Meanwhile, three Conservative MPs are calling for funding to be withdrawn from the Bureau of Investigative Journalism, which took part in the Newsnight investigation of child abuse allegations in north Wales.
Andrew Bridgen, Philip Davies and Bob Blackman signed the Commons motion stating that the BIJ had been "totally discredited", and so organisations such as Oxfam, Save the Children and the Joseph Rowntree Reform Trust should stop their donations.