BigBlueButton up to 3.0.22 ApiController ApiController.groovy handleJoinExistingUser existingUserID improper authentication

Summaryinfo

A vulnerability has been found in BigBlueButton up to 3.0.22 and classified as critical. This affects the function handleJoinExistingUser of the file bigbluebutton-web/grails-app/controllers/org/bigbluebutton/web/controllers/ApiController.groovy of the component ApiController. This manipulation of the argument existingUserID causes improper authentication. This vulnerability is tracked as CVE-2026-46355. The attack is possible to be carried out remotely. No exploit exists.

Detailsinfo

A vulnerability has been found in BigBlueButton up to 3.0.22 and classified as critical. Affected by this vulnerability is the function handleJoinExistingUser of the file bigbluebutton-web/grails-app/controllers/org/bigbluebutton/web/controllers/ApiController.groovy of the component ApiController. The manipulation of the argument existingUserID with an unknown input leads to a improper authentication vulnerability. The CWE definition for the vulnerability is CWE-287. When an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

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.

It is possible to read the advisory at github.com. This vulnerability is known as CVE-2026-46355 since 05/13/2026. The exploitation appears to be easy. The attack can be launched remotely. Technical details of the vulnerability are known, but there is no available exploit.

Upgrading to version 3.0.23 eliminates this vulnerability.

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Productinfo

Name

• BigBlueButton

Version

• 3.0.0
• 3.0.1
• 3.0.2
• 3.0.3
• 3.0.4
• 3.0.5
• 3.0.6
• 3.0.7
• 3.0.8
• 3.0.9
• 3.0.10
• 3.0.11
• 3.0.12
• 3.0.13
• 3.0.14
• 3.0.15
• 3.0.16
• 3.0.17
• 3.0.18
• 3.0.19
• 3.0.20
• 3.0.21
• 3.0.22

License

• free

Website

• Product: https://github.com/bigbluebutton/bigbluebutton/

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