"We believe his appearance was his desperate attempt to distract attention from the facts of the case," CBS officials said in a surprisingly harsh statement.
The scathing interview -- in which Stern called CBS boss Les Moonves a bully -- was in response to Moonves and CBS slapping him with a breach-of-contract lawsuit after he left the company for Sirius satellite radio earlier this year.
In it, they accuse him of hiding a contract clause in which Sirius would pay him several million dollars in stock based upon how many people subscribe to the service.
On Letterman, Stern blasted Moonves in a rant that lasted through several commercial breaks. "CBS took a third rate 'Love Boat' actor and made him CEO," Stern said, mocking his former boss' early career as an actor.
Stern sat for the interview wearing a T-shirt bearing images of Moonves and his wife, "Early Show" host Julie Chen, and the words: "I Hate Les Moonves Tour '06."
Stern says the lawsuit is Moonves' "vendetta" against him because the ratings for CBS' radio division collapsed after he left the company late last year.
"We hope, in subsequent coverage of that ['Late Show'] appearance, the media is not seduced or fooled in any way. Howard Stern has done something wrong and we intend to demonstrate this wrongful conduct in court," CBS officials said.