EEF-CVE-2026-82726 AshPhoenix get_subdomain maps a crafted or differently-cased Host header to an arbitrary tenant

Summary Permissive Regular Expression vulnerability in ash-project ashphoenix lets a remote client select the tenant an Ash application uses, or degrade the request, by sending a crafted Host header. AshPhoenix.Helpers.getsubdomain/2 stripped the root domain with String.replacehost, r/.?roothost/...