CVE-2026-46351
Received Received - Intake

Session Token Prediction in BigBlueButton

Publication date: 2026-07-16

Last updated on: 2026-07-16

Assigner: GitHub, Inc.

Description
BigBlueButton is an open-source virtual classroom. Prior to 3.0.21, bbb-web generated conference sessionToken values with insufficiently secure randomness in bbb-common-web/src/main/java/org/bigbluebutton/api/Util.java and bigbluebutton-web/grails-app/controllers/org/bigbluebutton/web/controllers/ApiController.groovy, allowing a session user to predict other users' conference session tokens and impersonate them. This issue is fixed in version 3.0.21.

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Meta Information

Published
2026-07-16
Last Modified
2026-07-16
Generated
2026-07-16
AI Q&A
2026-07-16
EPSS Evaluated
N/A
NVD
CVE-2026-46351
EUVD
EUVD-2026-44996

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
bigbluebutton bigbluebutton to 3.0.21 (exc)

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-330 The product uses insufficiently random numbers or values in a security context that depends on unpredictable numbers.

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Executive Summary

This vulnerability involves BigBlueButton generating conference session tokens with weak randomness before version 3.0.21. Attackers could predict these tokens and impersonate other users in sessions.

Detection Guidance

To detect this vulnerability, check if your BigBlueButton instance is running a version prior to 3.0.21. Run the command: bbb-conf --version. If the version is less than 3.0.21, the system is vulnerable. Additionally, inspect the files mentioned in the commit for insecure random token generation: bbb-common-web/src/main/java/org/bigbluebutton/api/Util.java and bigbluebutton-web/grails-app/controllers/org/bigbluebutton/web/controllers/ApiController.groovy.

Look for the use of RandomStringUtils.randomAlphanumeric() in these files. If found, the system is vulnerable.

Impact Analysis

An attacker could join sessions as another user, access sensitive data, or perform actions on behalf of the impersonated user. This could lead to unauthorized access to meetings, data breaches, or session hijacking.

Compliance Impact

This vulnerability could lead to unauthorized access to personal or sensitive data, violating GDPR's data protection requirements and HIPAA's safeguards for protected health information. Non-compliance may result in legal penalties and reputational damage.

Mitigation Strategies

Immediately update BigBlueButton to version 3.0.21 or later. This can be done by running the update command for your distribution, such as apt-get update && apt-get upgrade for Debian-based systems or yum update for RHEL-based systems.

After updating, verify the fix by checking the version again with bbb-conf --version and confirming the insecure random token generation code has been replaced with SecureRandom implementations.

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