BigBlueButton contains DoS via failed authToken validation

BigBlueButton is an open source web conferencing system. Versions prior to 2.4.3, are subject to Insufficient Verification of Data Authenticity, resulting in Denial of Service. An attacker can make a Meteor call to `validateAuthToken` using a victim's userId, meetingId, and an invalid authToken. This forces the victim to leave the conference, because the resulting verification failure is also observed and handled by the victim's client. The attacker must be a participant in any meeting on the server. This issue is patched in version 2.4.3. There are no workarounds.