How would you refer to the generic color of a carton/cardboard box?
Solution 1:
I love this question because I'm an artist and I hate a void in color-names. But, as common as these items are, the most easily understood terminology in the lexicon is: "plain-brown".
You could say "brown box" or, "brown bag", (and most people would get the idea) but there will always be some anal-case thinking: "What shade of brown?"
If the color in question was on your car, you might describe it as "tan", but if pressed to describe the shade of "tan" you'd say; "The color of a plain-brown box/bag". (US)
Solution 2:
Cardboard brown or #a58855 everyone who speaks English will immediately have an image that will be as close to each other as if you said 'fire engine red' or 'sky blue'
Solution 3:
The boxes are simply cardboard boxes, or maybe cardbox packing-cases. These are usually brown, so they are not usually qualified with a colour. If they need to be distinguished from white cardboard boxes, then [as I hinted in my earlier answer] they are brown cardboard boxes.
Original answer, pre-edit...
Although the box would probably simply be called brown, the colour is probably best described as manila (or "manilla" with two Ls).
(also Manila paper) Strong brown paper, originally made from Manila hemp
[ODO]
The outer layers of the corrugated cardboard are made from this paper. It does vary in colour between manufacturers (as the images show), but it is a suitable generic name.
Solution 4:
"Manila" usually refers to the color of file folders- a lighter vanilla color. This is Kraft Brown.
Solution 5:
If you want a named colour, some possibilities are beige, buff or fawn. All describe various shades of yellow-brown.