Zac Efron, best remembered for his role in 'High Shool Musical' and for being Vanessa Hudgens' boyfriend, embarked on a quiet stint in rehab earlier this year. Now that the news is out, rumors abound that it was not an alcohol problem that sent the good-looking actor to rehab but a raging cocaine addiction!

The problem got out of hand when Efron shot the flick 'Neighbors' this past April. The actor didn't show up on set of the Seth Rogen-starring film for a few days.

A source said, "It was common knowledge he was struggling with cocaine."

Three other sources confirmed to TMZ that it was indeed a cocaine problem that almost felled Efron.

But the actor didn't stop there. He was also playing around with Molly, which is the pure form of Ecstasy.

It's also reported that earlier this year, Efron went on a bender in Las Vegas and caused over 50 grand in damage to a room at the SkyLofts at the MGM Grand. Yikes. It sounds like he may have been on a downward spiral.

Efron's rep has not responded to requests for comment.

Let's look on the bright side, shall we? At least he went to rehab to address the problem.