Kristin Cavallari's The Hills co-stars are reportedly right in worrying about her alleged drug use.

A Cavallari acquaintance claims The Hills' star was "drinking and partying" last month throughout the All Points Worldwide Night Visions Oasis party at Coachella in Indio, CA, Us Weekly reported Friday.

"I saw her do a line of cocaine," the acquaintance told Us.

In addition, Cavallari apparently had a small problem with police one night during the music festival when she joined actor Jason Statham and several others for a ride in a golf cart.

"They got pulled over by the cops and were told to go home," the acquaintance told Us.

Cavallari's alleged drug use was addressed during The Hills' sixth-season premiere on Tuesday night, as co-stars Stephanie Pratt, Lo Bosworth and Audrina Patridge confronted Cavallari about suspected cocaine use during a trip the women took to Miami.

"First of all, that's not a real problem that I have," Cavallari told Zap2It in a Tuesday report.

"When Lo says in the episode that people had been talking about me doing coke, that was so out of left field. That was just about girls being catty and making s*** up. I wasn't even with them in Miami, so that was just crazy for me to stand there and listen to that."

Despite denials by Cavallari and her lawyer that she uses drugs, a source told Us that she hangs out with "party promoters" who are all "party animals."

"She's been sucked into the Hollywood scene," another source told Us. "She's surrounded by the leeches who enable her."