WWBN AVideo Unauthenticated Instagram Graph API Proxy via publishInstagram.json.php

WWBN AVideo is an open source video platform. In versions 26.0 and prior, the SocialMediaPublisher plugin exposes a publishInstagram.json.php endpoint that acts as an unauthenticated proxy to the Facebook/Instagram Graph API. The endpoint accepts user-controlled parameters including an access token, container ID, and Instagram account ID, and passes them directly to the Graph API via InstagramUploader::publishMediaIfIsReady(). This allows any unauthenticated user to make arbitrary Graph API calls through the server, potentially using stolen tokens or abusing the platform's own credentials.