[SEJeff]

They'd have to get background checks to serve on any committee which handles any sort of classified information. They'd need a clearance to head into the SCIF: https://en.wikipedia.org/wiki/Sensitive_Compartmented_Inform...

[munin]

That isn't really correct, as I understand it. The staffers get background checks, the senators and representatives take a secrecy oath in lieu of a process administered by the executive.

And really, with the separation of powers, how else would it work? The legislators are supposed to oversee things the executive does, do you think that it would be constitutional for the executive to tell the legislature to go fly a kite if the legislature asked to be told things? That, itself, could/would be unconstitutional...

edit: source: https://www.cia.gov/library/center-for-the-study-of-intellig...