Impersonation via handleJoinExistingUser in BigBlueButton <3.0.23
CVE-2026-46355 Published on August 20, 2026
BigBlueButton: Unauthenticated Session Hijack via Exposed /bigbluebutton/api/handleJoinExistingUser
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.
Vulnerability Analysis
CVE-2026-46355 can be exploited with network access, and requires small amount of user privileges. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have a small impact on confidentiality, a high impact on integrity, and no impact on availability.
Weakness Type
What is an authentification Vulnerability?
When an actor claims to have a given identity, the software does not prove or insufficiently proves that the claim is correct.
CVE-2026-46355 has been classified to as an authentification vulnerability or weakness.
Products Associated with CVE-2026-46355
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