High severity · published Jul 16, 2026
CVE-2026-46351
BigBlueButton: Insecure Randomness allows to guess user's conference session token and impersonate them
8.1
CVSS
0.5%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
None
Confidentiality
High
Integrity
High
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.5% · higher than 40% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
BI
bigbluebutton · bigbluebutton
< 3.0.21 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-46351
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-46351
github.com
https://github.com/bigbluebutton/bigbluebutton/commit/8457886c248aeba5597ee8749267602d6d117e98
github.com
https://github.com/bigbluebutton/bigbluebutton/releases/tag/v3.0.21
github.com
https://github.com/bigbluebutton/bigbluebutton/security/advisories/GHSA-7959-pf2v-xc4h
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