EXCLUSIVE

Chris Bosh and his wife are being sued by the porn magnates who created X-Art (admit it, you know it) ... who claim they rented a sick beach mansion from the NBA star that was literally filled with crap.

The people behind the suit are Colette and Brigham Field -- who created the erotic video website X-Art -- which features people hardcore banging each other in classy settings. It's so popular, they were profiled by GQ.

The Fields say they rented a 10,755 square foot super mansion in the Pacific Palisades owned by the Boshes in Dec. 2016 ... and plunked down $138k to cover the 1st month's rent ($46k) and the security deposit ($92k).

Problem is ... the Fields say shortly after moving in, they noticed crazy toxic mold, leaks, plumbing issues, rat droppings ... and worst of all -- the Internet access was horrible!!

The Fields say it was so bad they "had to seek medical assistance for sickness and rashes that they suffered from the time when the mold could be seen and smelled."

In the lawsuit, filed in L.A. County Superior Court and obtained by TMZ Sports, the Fields say they tried to get their security deposit back but the Boshes refused ... and have since let other people stay in the home.

They're demanding the $92k deposit back plus unspecified damages. We reached out to the Boshes for comment, but no word back.