The big deal is that there is the appearance of him sharing info with the Russians that was not his to share because it came from a source (prolly Israel) that was emphatic that it not be shared with anyone.

Personally, I don't think he did it out of malice. I think his insecurity and internal demands for attention led him to do it. The man has no impulse control and wants to impress everyone and have them love him. I imagine it went something like, "Lavrov, you wouldn't believe. I get the best, THE BEST, intelligence. Nobody ever got intelligence like I get. Like this bomb in a notebook thing we got from a partner's intelligence, out of an ISIS infiltrator in WhereTF, Syria..."

We didn't know as much about suspected misdeeds pertaining to Watergate when we established the Senate Select Committee on that as we know about suspected misdeeds by the three year old tyrant in the White House now, so where the hell is our Senate Select Committee?