Who was CNN's source for hit piece on Nunes that got them sued?

Ace of Spades:

CNN published a story that Lev Parnas, an indicted "associate" of Rudy Giuliani, is willing to testify that Nunes met with a Ukrainian prosecutor in Vienna to collect kompromat on Joe Biden.
Which is also known as "What Democrat Firm FusionGPS Does Every Damn Day."
In addition to this not being illegal, the story suffers from another defect:
It's provably untrue.
Not that CNN has cared about that sort of thing for years.

In the 47-page filing, Nunes says he never traveled to Austria in 2018 and that he never met with or spoke to Viktor Shokin, the former prosecutor. The lawsuit says that during the time Parnas claimed Nunes was in Vienna, the congressman was actually in Libya and Malta. Pictures from those trips are included in the filing.

One commentator pointed out that this was "Michael Cohen in Prague" all over again.
The media -- which is no longer distinguishable from the Democrat Party they service -- is of course willing to publish anything, and doesn't learn from past mistakes because they're not mistakes. They fully intend to publish false "news" and slanders in service of the Democrat Party.

Meanwhile, CNN's enormously fat palace eunuch Brian Stelter retweeted another hugely fat liberal's remarkable claim that, unlike the right, the left has no infrastructure whatsoever for pushing conspiracy theories.
People began tweeting Fat Joker's own forays into leftwing conspiracy theorizing, including his fact-free jazz-odyssey noodlings about Trump's Secret Heart Attack, as well as he claims about the First Lady being Missing.
...

When a story is described as demonstrably false CNN should have a hard time trying to claim that their source should be protected.  Ace seems to think that CNN knew the story was false or in the exercise of reasonable care should have known.  What this looks like is an attempt to shut down an effective member of Congress from participating in defending the President.  At this point, it is hard to see a reasonable explanation for why CNN ran this story.