The headline is incorrect.

Clapper did not leak the dossier. Nor does the House Report say that he did. This is what they found

(U) Finding #44: Former Director of National Intelligence James Clapper. now a CNN national security analyst, provided inconsistent testimony to the Committee about his contacts with the media.

They are not saying he lied to Congress.

Here's the discussion, you find this by searching the report for Tapper https://docs.house.gov/meetings/IG/IG00/20180322/108023/HRPT-115-1.pdf

CNN reported on January 12, 2016, that President-elect Trump was briefed on classified information indicating that the Russians have compromising personal or financial information that the Russians could use against President-elect Trump..... former Director of National Intelligence James Clapper admitted that he confirmed the existence of the dossier to the media ..... When initially asked about leaks rel~ted to the ICA in July 2017, former ONI Clapper flatly denied "discuss ling] the dossier [compiled by SteeleJ or any other intelligence related to Russia hacking of the 2016 eledion with joumalists."~5 Clapper subsequently acknowledged discussing the "dossier with CNN journalist Jake Tapper," and admitted that he might have spoken with other journalists about the same topic.45

Footnote 45 says Regarding his communication with Tapper about the dossier, Clapper stated: "I don't know exactly the sequence there, but It was pretty close to when we bri~fed it and when It was out all over the place. The media had it by the way. We were kind of behind the power curve, because the media, many media outlets that I understood had that, had the dossier for some time, as did people on the Hill."

CNN did not publish the dossier. Buzzfeed did.