Hacker Smealum has created the SSSpwn exploit for 3DS firmware version 6.3, which was released about 6 months back. It may work on newer firmware additions, but that hasn't been tested yet. The best news is, Smealum is out to offer a hack that allows for homebrew creation, but not piracy. That's exactly what this SSSpwn exploit does.

"It’s the sweet spot that gives us just enough to get awesome homebrew code running in arm11 user mode, but not enough to break the system bad enough to let anyone do whatever the hell they want. As such, I personally have no qualms with releasing the exploit into the wild."

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