The HBO documentary Kurt Cobain: Montage of Heck has been receiving mixed reviews on the film festival circuit, but ahead of its May 4 television premiere it has been revealed that the film's soundtrack will feature "a mind-blowing 12-minute acoustic Cobain unheard track," according to filmmaker Brett Morgen.

No other details have been given regarding the song other than the fact that it will appear on the soundtrack. No date has been set for the release of the soundtrack either.

Speaking about the documentary's score to Rolling Stone, Morgen said that it was all comprised of unreleased music from the late Nirvana frontman.

"They don't have titles. Before people saw the movie, there were these weird press releases focusing on the unreleased music. And it's like: It's a movie. We're not going to stop it and play a song for four minutes," Morgen said. "But nobody in Kurt's life -- not his management, wife, bandmates -- had ever heard his Beatles thing [a snippet of 'And I Love Her']. I found it on a random tape. It's a Paul [McCartney] song. How's that for shattering the myth?"

In related news, a supposed unreleased Nirvana track was uploaded to YouTube by a self-described hacker last month. The hacker claimed that the song, titled "Flacid Bone" was scrapped by the band because Cobain hated the song and that it was stolen from Courtney Love.

Love, who is a part owner of Cobain's music rights, has since confirmed that the song is a fake and that she had never been in possession of the song nor was she ever hacked. According to TMZ, she has reportedly filed a lawsuit and is working to track down the person who leaked it.

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