CVE-2026-46355

BigBlueButton: Unauthenticated Session Hijack via Exposed /bigbluebutton/api/handleJoinExistingUser

Published: Aug 20, 2026Updated: Sep 16, 2026 Sources: CVE List NVDCWE-287

7.1HIGH

Description

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.

No summary for this CVE yet.

CVSS Vector Breakdown

Exploitability

AV:NAttack Vector

Network

AC:LAttack Complexity

Low

PR:LPrivileges Required

Low

UI:NUser Interaction

None

Scope

S:UScope

Unchanged

Impact

C:LConfidentiality

Low

I:HIntegrity

High

A:NAvailability

None

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Weaknesses

CWE-287

Affected Products

bigbluebutton

oss-projectaka bbb

bigbluebuttonOn-premWeb App

Communications / video-conferencing

Exploitability

No known exploits, KEV entries, or remediation guidance available for this vulnerability yet.

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Attack Graph

Products CVE Techniques Tactics

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MITRE ATT&CK

2 techniques

Initial Access

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References

https://github.com/bigbluebutton/bigbluebutton/security/advisories/GHSA-38fw-2gq7-ccgr

github.com

https://github.com/bigbluebutton/bigbluebutton/commit/972b04e474e195cbd708b5b3f0485fe528a1a85b

github.com

https://github.com/bigbluebutton/bigbluebutton/releases/tag/v3.0.23

github.com

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