I'm not sure what you mean by the lounge in CMB. There are three lounge there: one is the business class lounge and two others.

One states: "Due to the ongoing development of facilities at Bandaranaike International Airport, the Serendib Lounge is currently only available to customers traveling in First and Business Class cabins on Srilankan Airlines and other oneworld members flights. Emerald and Sapphire status customers traveling in Economy Class cabins on long and medium haul flights are invited to use the Serendiva Lounge."

The other states: "Due to the ongoing development of facilities at Bandaranaike International Airport, SriLankan Airlines Flysmiles Platinum and Gold and oneworld Emerald and Sapphire status customers traveling in Economy Class cabins on long and medium haul flights are invited to use the Serendiva Lounge."