CVE-2026-46355: Bigbluebutton

High severity, CVSS 7.1. EPSS: 0.4% chance of exploitation in the next 30 days.

BigBlueButton is an open-source virtual classroom. Prior to 3.0.23, BigBlueButton exposed /bigbluebutton/api/handleJoinExistingUser through bigbluebutton-web/grails-app/controllers/org/bigbluebutton/web/controllers/ApiController.groovy. A requester able to supply an existingUserID for an active participant could reuse that participant's session and impersonate the participant in the same meeting because handleJoinExistingUser was a routable controller action rather than a private helper. This issue is fixed in version 3.0.23.

Affected products

• Bigbluebutton Bigbluebutton: before 3.0.23 (fixed in 3.0.23)

Published 2026-08-20. Last modified 2026-09-16.