Like all non-LTS releases, Ubuntu 15.10 (Wily Werewolf) was supported for 9 months and this period ends today. This means Ubuntu Security Notices will no longer include information or updated packages for Ubuntu 15.10.
If you're still using Ubuntu 15.10, it's recommended you upgrade to Ubuntu 16.04, which is supported until April 2021. For how to upgrade to Ubuntu 16.04, see THIS page.
via Web Upd8 - Ubuntu / Linux blog http://ift.tt/2afGt7H