WWBN AVideo Authentication Bypass via User-Agent Header

WWBN AVideo (current e01e41ecc and earlier) makes three login-time security controls depend solely on the client-supplied User-Agent header. The isAVideoEncoder()/isAVideoMobileApp() checks match HTTP_USER_AGENT against a hardcoded literal ("AVideoEncoder"/"AVideoMobileApp") with no IP check or shared secret. An attacker who submits valid credentials and sets User-Agent: AVideoEncoder bypasses two-factor authentication, skips brute-force captcha escalation, and avoids being recorded in the login/device audit history. No patch is available at the time of publication.