For all you users that downgraded to 8.4.1 just to prepare for the iOS 8.4.1 jailbreak it could soon be a reality. The developer @qwertyoruiop on Twitter has released his source code of the his jailbreak code named “Yalu“. Qwertyoruiop is the same developer that found 2 zero day vulnerabilities in OS X Yosemite back in August. So he is a trusted developer. 

Right now “Yula” is very limited to what it can do. The developer has posted pictures of Cydia running on his device. But has stated

latest Yalu git commit does a jailbreak & extracts a .tgz to /. Make sure not to install cydia with it. OpenSSH is fine.

the jailbreak is pretty much tethered at this point (since it lasts 1 boot), but making a full untether at this point is trivial

So right now the jailbreak is a bit of work and personally I would not advise using it till its pushed out as a click and run tool. The reason is iOS 8.4.1 is not being signed. So if it messes up you have to update and can’t go back. If you want to check out “Yula” it can be found here. But remember it’s just a source code and not a full tool.