subdomain Enumaration via side channel alerting security bug which is critical

[nguyenblacks]

the AlgoraWeb.Endpoint contains a logic flaw in the canonical_host/2 function its pefroms a database lookup Algora.Accounts.get_user_by_handle/1 and triggers a cricitical security alert Algora.Activities.alert/2 based on weather ,e a subdomain matches a valid user handle