A technique manages user authentication via common authentication framework circuitry. The technique involves receiving, by the common authentication framework circuitry, authentication requests from client devices of users belonging to multiple enterprises, the authentication requests including user identifiers identifying the users belonging to the multiple enterprises. The technique further involves accessing, by the common authentication framework circuitry, entries of an authentication policy database to select authentication policies for the authentication requests. Selection of the authentication policies is based at least in part on the user identifiers of the authentication requests. The technique further involves invoking, by the common authentication framework circuitry, authentication services in accordance with the selected authentication policies to perform user authentication operations in response to the authentication requests from the client devices.