GHSA-m27g-v28p-f9fx: OmniAuth: Host Header Injection Vulnerability

OmniAuth is a flexible authentication system utilizing Rack middleware. Prior to 2.2.0, OmniAuth derives provider callback URLs from request-controlled host information when neither a fixed fullhost nor framework-level incoming host validation is configured. A remote unauthenticated client can supply a forged Host header, creating a host header injection risk in applications whose web framework does not verify incoming host headers. Applications using appropriately configured Rails host authorization or a fixed fullhost are not affected by this path. This issue is fixed in version 2.2.0.