>their listing in a publicly accessible database may constitute one of the largest mass breaches of personal data of an intelligence service in recent history
The CIA maintains their own personal files and does not use the OPM. Granted, the theory is that China could cross reference the OPM hack data with foreign diplomats coming to China to find which ones are the spooks, but the data on spooks hasn't been compromised. At least not that we are aware of.
Former NSA senior counsel Joel Brenner called the material “a gold mine for a foreign intelligence service,” declaring, “This is not the end of American human intelligence, but it’s a significant blow.” (Points to the CIA, which refused to have anything to do with the OPM and thus kept its own employees’ information safe.)
Pretty sure the OPM breach holds that record.