Which of the following problems is not addressed by using OAuth (Open Standard to Authorization) 2.0 to integrate a third-party identity provider for a service?

OAuth 2.0 is an authorization framework, not an authentication protocol; it does not address how Resource Servers authenticate end users directly. Authentication is handled by protocols like OpenID Connect (OIDC) built on top of OAuth 2.0, meaning OAuth alone does not solve the problem of Resource Servers needing passwords or credentials to authenticate end users - that problem remains unless a separate identity layer is added.

OAuth 2.0 does address granular access revocation by allowing individual access tokens or refresh tokens to be revoked per user or per scope, rather than revoking all users from a third party at once.

OAuth 2.0 mitigates the blast radius of a third-party compromise because tokens are scoped and time-limited, reducing but not necessarily eliminating the risk that a third-party breach compromises all service users.

OAuth 2.0 enables guest users to authenticate via a third-party identity provider through its authorization flows (e.g., authorization code flow), allowing federated access without requiring accounts native to the resource server.