This leaks comes from Gamestop which has a poster up of the downloadable content. The poster shows off the 4 new maps Fog, Containment, Bayview, and Ignition. Also two new weapons the Maverick AR and the Sniper Rifle, to top it all off you will get a new episode in Extinction called Night Fall. The Onslaught Downloadable Content for Call of Duty Ghost will be releasing January 28th, and coming exclusively to Xbox One one month earlier.
Source: CharlieIntel