vxjasonxv wrote in a comment:
I never knew gimp didn't support CYMK....
You should hound the devs to add that in XD, that's pretty important to some people.
(Hint: The perfect people to send to the OSS world.)
There have been requests for it (after all, CMYK is a must for any design professional who works with color prints), one even with a cash reward, but none has been honored so far.
In fact, a professional need being ignored or undervalued is nothing new or surprising in the history of GIMP. Film industry once showed interest in GIMP 1, and offered a lot of pro-grade features for inclusion in GIMP 2. The GIMP project initially cooperated, then later flipped the table saying the additional requirements necessary for the new features weren't what existing GIMP users (read: mostly amateurs and non-professional geeks, back in the days of GIMP version 1) “cared about.” Disappointed, the film industry withdrew its support, and its contribution made the way into a spinoff called Film GIMP (now CinePaint).
This was around year 2000 or so. Now fast foward to these days: More and more people are using CinePaint for its superior imaging capabilities: It supports 16-bit color channels, compared to GIMP's 8-bit channels; it supports both CIE L*a*b and CMYK colorspaces; it does color management for you; it removes dust and scratches (crucial for film scans). And now people are asking the GIMP project for the same features, which the project says will be included in a “future version.” Do we sense an unfortunate outbreak of shortsightitis here? I thought so.
Hopefully the GIMP project learned the valuable lesson: Do not turn down an important feature simply because current users don't “care about it”—chances are, they will, in a near future.