In the Zoom Client through 4.4.4 and RingCentral 7.0.136380.0312 on macOS, remote attackers can force a user to join a video call with the video camera active. This occurs because any web site can interact with the Zoom web server on localhost port 19421 or 19424. NOTE: a machine remains vulnerable if the Zoom Client was installed in the past and then uninstalled. Blocking exploitation requires additional steps, such as the ZDisableVideo preference and/or killing the web server, deleting the ~/.zoomus directory, and creating a ~/.zoomus plain file.
https://twitter.com/zoom_us/status/1148710712241295361
https://twitter.com/moreati/status/1148548799813640193
https://news.ycombinator.com/item?id=20387298
https://bugs.chromium.org/p/chromium/issues/detail?id=951540
https://blog.zoom.us/wordpress/2019/07/08/response-to-video-on-concern/
https://assets.zoom.us/docs/pdf/Zoom+Response+Video-On+Vulnerability.pdf