Grafana OnCall through 1.16.11 contains an unauthenticated access vulnerability that allows remote attackers to obtain a valid PluginAuthToken by sending a POST request to the internal plugin install endpoint using hardcoded default stack_id and org_id values present in the public source tree. Attackers can leverage the acquired token to authenticate against all internal API endpoints, create arbitrary Admin users via the user-context header bootstrap path, revoke the legitimate plugin token, and redirect OnCall-to-Grafana API calls to an attacker-controlled host by overwriting the organization's grafana_url and api_token.