It's not hard to cut them down. We cut a 12" wide cab into a 5" wide to fill a space that otherwise would have been wasted. I use the 5" to store cookies sheets and such so it's perfect.
You'll need to get the right bits to redrill the new holes but that's not too difficult. I would be concerned with the door fitting correctly more than anything. Depending on which corner cab you have, it should come with a 2" filler piece so taking only 1" off might be ok. I'd def measure and measure again before cutting!
Just FYI, if you do cut it and it doesn't fit, IKEA will take it back if you have all the pieces! We found this out when we cut a piece wrong and brought it back with some other stuff to return. We didn't expect them to take the cut piece, but they told us that as long as we had the cut part + the original piece, they would refund us the $$ no problem.
Good luck.

Not the right cabinet line for you if it does not fit. Traditional corner wall cabinets are 24” wide. From almost every company on the planet.

IKEA cabinets are easy to successfully alter.

Who designed the kitchen I have done many Ikea kitchens and not one time have I had to alter a corner cabinet in fact I rarely have to alter anything with proper planning.

Thanks all repliers!

Hillside House, I am doing third-party doors (none of IKEA's styles worked with my style) so altered dimensions will be made up there. The corner does concern me a bit though. It's the 26" corner cab. It also crowds my exhaust hood on the left side of the corner (window on the right side) so trimming helps on both sides.

sh Nice to know they take back if it doesn't work. thx

By 26" are you referring to the blind corner that is 26" by 47"? Or are you asking about the 36" lazy susan corner?