High severity · published Jul 16, 2026
CVE-2026-46353
BigBlueButton API checksum bypass via presentationUploadExternalUrl
8.1
CVSS
0.5%
EPSS
No
On KEV
Description
BigBlueButton is an open-source virtual classroom. Prior to 3.0.21, bbb-web checksum validation could be bypassed when a presentationUploadExternalUrl parameter was supplied to API request handling in CreateMeeting.java and ValidationService.java, allowing a user to send valid requests to some endpoints without a checksum. 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 41% 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-2026-46353
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-46353
github.com
https://github.com/bigbluebutton/bigbluebutton/commit/36fd1b407488a0c56ce620b91184d5a8aea68b3d
github.com
https://github.com/bigbluebutton/bigbluebutton/releases/tag/v3.0.21
github.com
https://github.com/bigbluebutton/bigbluebutton/security/advisories/GHSA-43hc-5g2m-cqff
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