As it prepared to broadcast a rare on-air correction Sunday for a now-discredited “60 Minutes” report, CBS News acknowledged on Friday that it had suffered a damaging blow to its credibility. Its top executive called the segment “as big a mistake as there has been” in the 45-year-old history of the celebrated news program.

The executive, Jeff Fager, conceded that CBS appeared to have been duped by the primary source for the report, a security official who told a national television audience a harrowing tale of the attack last year at the American diplomatic mission in Benghazi, Libya. On Thursday night it was disclosed that the official, Dylan Davies, had provided a completely different account in interviews with the F.B.I., in which he said he never made it to the mission that night.

After that revelation, CBS decided to take multiple actions Friday. It removed the report from the CBS News website, and the correspondent for the segment, Lara Logan, appeared on the CBS morning news show to apologize personally for the mistakes in the report. And the company’s publishing division, Simon & Schuster, said it was suspending publication of a book by Mr. Davies, in which he tells the same narrative he recounted on “60 Minutes.”

“It’s a black eye and it’s painful,” Mr. Fager said in a phone interview. He declined to say whether there would be negative consequences for any of the journalists involved.