"In a newly unsealed declaration from September, former senior counterintelligence FBI agent Bill Priestap confirmed that the FBI received a copy of the first 33 pages of the dossier in December 2016 from McCain.
In another filing, David Kramer – a former State Department official and McCain associate – said in a Dec. 13, 2017, deposition that the dossier was given to him by author and former British spy Christopher Steele, which he then provided to more than a dozen journalists at outlets including CNN, BuzzFeed and The Washington Post. The details were first reported by The Daily Caller."
https://www.foxnews.com/politics/court-files-reveal-role-of-mccain-aide-in-spreading-anti-trump-dossier