Vulnerability · Published Jul 16, 2026 · Assigned by GitHub_M

CVE-2026-46353BigBlueButton API checksum bypass via presentationUploadExternalUrl

High 8.1

In plain English

A high-severity improper access control in bigbluebutton from bigbluebutton. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 41% of all known vulnerabilities).

Severity (CVSS 3.1)8.1High

Exploit odds (30 days)0.5%top 58.7% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official 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.

Affected products (as reported)

Vendor	Product	Versions
bigbluebutton	bigbluebutton	< 3.0.21

Weakness: CWE-284 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N

References

https://github.com/bigbluebutton/bigbluebutton/security/advisories/GHSA-43hc-5g2m-cqff x_refsource_CONFIRM
https://github.com/bigbluebutton/bigbluebutton/commit/36fd1b407488a0c56ce620b91184d5a8aea68b3d x_refsource_MISC
https://github.com/bigbluebutton/bigbluebutton/releases/tag/v3.0.21 x_refsource_MISC