In the midst of releasing new updates to Redstone 2 and Cumulative Updates to Redstone 1 Microsoft is also working on testing new Cumulative Update for its Threshold Branch for Windows 10 and Windows 10 Mobile.
The company is internally testing new CU Build 10586.671 which has been compiled on Friday 21st October. Earlier we had confirmed that the company is internally testing .639 last week, so it a big jump from the previous tested CU for Threshold Branch.
— BuildFeed (@buildfeed) October 27, 2016
We are currently not sure as to what fixes will the Cumulative Update build bringing for the Threshold Branch. We will update this article once we get our Hands on the Changelog. If the company does not find any issues during internal testing then the Threshold Branch could see a Cumulative Update released in the coming weeks.