Tor 0.2.8.7 fixes an important bug related to the ReachableAddresses option. The new bridge authority is “Bifroest” and replaces a retiring bridge authority. Packages should be available over the next week or so. The “Tonga” bridge authority has been retired, and all bridges are strongly encouraged to upgrade. You can download the source from the Tor website and download the latest version of the Tor software. The latest version has been released on August 2, 2016.”]
Source: https://blog.torproject.org/tor-0287-released-important-fixes