Capgo - Unauthenticated Channel Enumeration and App Oracle via GET /channel_self

Capgo before 12.128.2 contains an information disclosure vulnerability in the /functions/v1/channel_self endpoint that allows unauthenticated attackers to enumerate non-public channel names and determine app existence and subscription status. Remote attackers can send GET requests with arbitrary app_id parameters to disclose internal rollout channels, enumerate valid applications across tenants, and leak billing status without authentication or device binding.