Well if the leaker didn't have that level of clearance, how did he/she gain access to the information? There is one possibility, Congressmen, of both houses, do not require clearances, (many of them wouldn't stand a chance in hell of getting one) to see classified information. They do have to specifically ask for it though. Unless of course they pick it up in one of the required "leadership" briefings from the executive branch. Their staff requires clearances, but they don't. Of course they likely blab to their staffers, cleared or not.
That was explained in the rest of the post. Laxity.