A security contractor told 60 Minutes programme he had been present during the attack, but later gave a conflicting statement to investigators with the FBI.
Reporter Lara Logan said it was a “mistake” to put the contractor on air.
Four Americans died in the attack, including a US ambassador.
Lara Logan, a reporter for 60 Minutes, a storied current affairs programme, said on Friday a source had provided false information during a report aired on October 27.
The security official, identified as Dylan Davies, said he had been at the US compound during the September 11, 2012, attack.
Dylan Davies reported he had witnessed the attack, fought off an assailant, and later viewed the body of US Ambassador Christopher Stevens.
But other news outlets subsequently revealed Dylan Davies had told FBI investigators and his employers he was not at the Benghazi compound the night of the attack.
“The most important thing to every person at 60 Minutes is the truth, and today the truth is we made a mistake,” Lara Logan told a CBS morning news programme on Friday.
“Nobody likes to admit they made a mistake, but if you do, you have to stand up and take responsibility and you have to say that you are wrong. And in this case, we were wrong.”
Lara Logan added that 60 Minutes planned to air a correction on its regular broadcast on Sunday evening.
CBS News chairman Jeff Fager told the New York Times Dylan Davies had lied to the network.
“There are people in the world who try to deceive others,” he said.
“We believe we have a really good system to guard against that. This guy got through that.”
Meanwhile, publication of a book written by Dylan Davies about the 2012 attack has been halted.
Threshold Editions said on Friday it was suspending publication of The Embassy House: The Explosive Eyewitness Account of the Libyan Embassy Siege by the Soldier Who Was There.
The book, written under the pseudonym Sgt Morgan Jones, was released on October 29.
The attack against the US consulate – which resulted in the death of Christopher Stevens, another state department worker, and two former Navy Seals – was originally said to have grown out of violent anti-American protests sparked by an anti-Islam film produced in the US.
It was later revealed to have been an organized, pre-planned assault by militia forces.
The US filed charges against a Libyan militia chief, Ahmed Abu Khattala, in August and an unknown number of other alleged attackers have also been charged.
Republicans denounced President Barack Obama’s handling of the incident, accusing the administration of failing to provide adequate security at the Benghazi compound and of neglecting to send a force to rescue the personnel after the attack began.
Also, the Republicans accused Barack Obama and his fellow Democrats of downplaying the attack in order to protect his 2012 re-election campaign.
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