BigBlueButton is an open-source virtual classroom. Versions prior to 3.0.24 have a missing authorization that allows viewers to inject/overwrite captions Version 3.0.24 tightened the permissions on who is able to submit captions. No known workarounds are available.
https://github.com/bigbluebutton/bigbluebutton/security/advisories/GHSA-q387-2q28-mg33