Today Microsoft announced the addition of .NET Core and ASP.NET Core to their suite of ongoing bounty programs. They are offering a bounty on the Windows and Linux versions of .NET Core and ASP.NET Core starting on September 1, 2016. For complete details please see the following:
Announcing a Microsoft .NET Core and ASP.NET Core Bug Bounty
J.C. Hornbeck, Solution Asset PM
Microsoft Enterprise Cloud Group