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CVE-2026-27466 Detail

Description

BigBlueButton is an open-source virtual classroom. In versions 3.0.21 and below, the official documentation for "Server Customization" on Support for ClamAV as presentation file scanner contains instructions that leave a BBB server vulnerable for Denial of Service. The flawed command exposes both ports (3310 and 7357) to the internet. A remote attacker can use this to send complex or large documents to clamd and waste server resources, or shutdown the clamd process. The clamd documentation explicitly warns about exposing this port. Enabling ufw (ubuntu firewall) during install does not help, because Docker routes container traffic through the nat table, which is not managed or restricted by ufw. Rules installed by ufw in the filter table have no effect on docker traffic. In addition, the provided example also mounts /var/bigbluebutton with write permissions into the container, which should not be required. Future vulnerabilities in clamd may allow attackers to manipulate files in that folder. Users are unaffected unless they have opted in to follow the extra instructions from BigBlueButton's documentation. This issue has been fixed in version 3.0.22.


Metrics

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CVSS 4.0 Severity and Vector Strings:

NIST CVSS score
NIST: NVD
N/A
NVD assessment not yet provided.

References to Advisories, Solutions, and Tools

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URL Source(s) Tag(s)
https://github.com/bigbluebutton/bigbluebutton/commit/f3d33d94a9682e87c7d41f55700b19d61e1ab8b4 GitHub, Inc.
https://github.com/bigbluebutton/bigbluebutton/security/advisories/GHSA-wmhx-qw2p-w6gc GitHub, Inc.

Weakness Enumeration

CWE-ID CWE Name Source
CWE-668 Exposure of Resource to Wrong Sphere GitHub, Inc.  

Change History

1 change records found show changes

Quick Info

CVE Dictionary Entry:
CVE-2026-27466
NVD Published Date:
02/21/2026
NVD Last Modified:
02/21/2026
Source:
GitHub, Inc.