Hollywood mega-couple BARBRA STREISAND and JAMES BROLIN are hiding a secret shame, The National ENQUIRER has learned.

While superstar diva Barbra and her husband of 16 years reside in a fabulous $100 million Malibu, Calif. estate, his tragic son, Jess, is homeless and eating out of garbage cans!

The grossly overweight 42-year-old, one of James’ sons from his first marriage, lives on the streets of Ojai, Calif., and sleeps wherever he can find shelter, an undercover ENQUIRER investigation has discovered.

On Sept. 8, The ENQUIRER spotted a disheveled Jess dumpster diving for scraps that had been tossed in the trash.

 “Nobody can believe Jess’ stepmother and father are letting him live on the streets,” friend Susan Trejo told The ENQUIRER. “I think his older brother (actor) Josh Brolin should be helping out too! How could they let him live like this?”

An insider added: “Jess will sometimes sleep in fields, behind stores, wherever he can bed down. It’s very cold here in the valley at night and it’s extremely hot during the day. Nobody should live this way.”

But a family spokesman tells The ENQUIRER that James, 74, has never given up on his son, despite Jess spurning all offers of help – including from stepmother Barbra.

“We have offered help and support, and we continue to do so. We love him very much and want only the best for him,” the rep said.

Until recently, Jess bunked down in his banged-up blue 1981 Toyota pickup truck. But it fell apart.

The ENQUIRER’s investigation uncovered Jess – who was said to have inherited a six-figure trust fund after the death of his mother, wildlife activist Jane Cameron Agee – sleeps in a dump behind a local restaurant and surrounded by garbage. He is receiving some help from a local Ojai community assistance program, sources said, but his living situation continues to deteriorate.

“She and Brolin are worth $400 million, and own one of the largest compounds in Malibu, ” a Hollywood insider told The ENQUIRER. “People will be asking why they can’t put this poor troubled man in one of their spare bedrooms.”

For ALL the details and to see the heart-rending pictures – it’s only in the new ENQUIRER – on sale now!