A user on NeoGAF posted a screenshot that reportedly shows Call of Duty: Ghosts only using roughly a maximum of 2 GB RAM with everything maxed out.
It was also noted that the game has a "lock" that prevents gamers who have specifications less then 6 GB RAM from launching the game.
While this does seem odd, it doesn't make sense as to why a company will limit players from playing the game if their hardware is capable of it. It will only alienate potential customers. Activision still hasn't responded about this issue, but perhaps there are other factors that made them decide that 6 GB of RAM would be the baseline requirement.
Aside from this, a recent issue surroundting the game involves its "upscaled 720p to 1080p" resolution in the Xbox One. Infinity Ward's Mark Rubin also expounded on this earlier today.
Call of Duty: Ghosts is coming for Wii U, Windows, Playstation 3 and Xbox 360 on November 5th, Playstation 4 on November 15th, and Xbox One on November 22nd.