HivePress Authentication < 1.1.5 - Unauthenticated Authentication Bypass via 'access_token' Parameter to Facebook Authenticator

Description

The HivePress Authentication plugin for WordPress is vulnerable to Authentication Bypass via the access_token parameter in all versions up to, and including, 1.1.4. This is due to the authenticate_user function's Facebook authenticator resolving third-party identity by forwarding the attacker-supplied access_token to the Facebook Graph API and trusting the returned email and ID verbatim, without performing any application ID or audience validation — specifically, no /debug_token verification and no comparison of the token's app_id against the configured hp_facebook_app_id. This makes it possible for unauthenticated attackers to authenticate as any existing WordPress user, including administrators, whose email address is associated with a Facebook account for which the attacker can obtain any valid access token. Important Note: To exploit the vulnerability, the attacker must obtain the victim's access token.