The Halo 5 beta is not active at the moment, but its developer 343 Industries is still updating the client for its own purposes—accidentally spilling details about the upcoming game's multiplayer modes to the public in the process.
Over the weekend, Halo 5: Guardians details leaked out thanks to Microsoft's updating procedures, which saw the client receive a wealth of new content.
If you have the client installed, you can examine some of the new content.
“This Halo 5: Guardians content is part of our ongoing private, external testing for multiplayer,” said an official Microsoft spokesperson. “We will continue to rigorously test Halo 5: Guardians to ensure the best possible experience for fans at launch.”
Some of the content being leaked includes images of the game's Warzone multiplayer mode's menu, which shows off the Spartan customization screen and more.
Halo 5: Guardians comes out on October 27. It's exclusive to the Xbox One.