Kendall Jenner isn't nude on THIS horse but in some X-rated pix that leaked online today she's buck naked on a different horse, on a beach, and on the top of everyone's daily news feeds!

Here's what went down -- it's not something scandalous, like a boyfriend revenge-posting naked pix -- Kendall was modeling. She was doing an artsy shoot for an upcoming Victoria's Secret coffee table book. Frankly, we don't understand what hot girls running around naked has to do with selling underwear, but somehow VS has morphed into a modern-day Playboy ... and yet Playboy isn't even doing nude photo shoots anymore!

So anyway, a photographed called Russell James took pix of the lovely 22-year old completely unclothed, on an unnamed beach, running and in some frames, riding a horse. The pix "leaked" online (or perhaps it's the best "organic" marketing EVER for a coffee table book) and the Twittersphere can hardly take it.

People are laughing AND crying! And shaming ... take a look at some of the reactions:

Could all of this be feeding into Kendall's self-admitted insecurities and could it have something to do with the reason she left New York Fashion Week early? Actually, we think not -- because that saddle she was back in today is a Longchamp photo shoot in Paris. She's working, bitches!