← Vulnerability feed

Vulnerability record · CVE-2026-27466 · published 21 February 2026

CVE-2026-27466: Bigbluebutton exposure of resource to wrong sphere vulnerability

Bigbluebutton · Bigbluebutton

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.

8.2 CVSS 3.1 High EPSS 0.58% · top 54.3% CWE-668 · Exposure of resource to wrong sphere
8.2CVSS 3.1 base score
0.58%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
2References, 1 tagged exploit
17 Jun 2026Last modified by NVD

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.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/bigbluebutton/bigbluebutton/commit/f3d33d94a9682e87c7d41f55700b19d61e1ab8b4 Patch
https://github.com/bigbluebutton/bigbluebutton/security/advisories/GHSA-wmhx-qw2p-w6gc ExploitPatchVendor Advisory

Track CVE-2026-27466 inside VULONE

Watch it alongside the ransomware crews, C2 infrastructure and forum chatter that reference it, query it through the API and pull it into your SIEM over TAXII.

Start free Open in platform

Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

9.8CVE-2020-27602Bigbluebutton injection vulnerabilityBigBlueButton before 2.2.7 does not have a protection mechanism for separator injection in meetingId, userId, and authToken.EPSS 1.4%9.8CVE-2020-27605Bigbluebutton vulnerabilityBigBlueButton through 2.2.28 uses Ghostscript for processing of uploaded EPS documents, and consequently may be subject to attacks related to a "schw…EPSS 1.2%9.8CVE-2020-12443Bigbluebutton path traversal vulnerabilityBigBlueButton before 2.2.6 allows remote attackers to read arbitrary files because the presfilename (lowercase) value can be a .pdf filename while th…EPSS 3.7%8.8CVE-2023-42803Bigbluebutton unrestricted file upload vulnerabilityBigBlueButton is an open-source virtual classroom. BigBlueButton prior to version 2.6.0-beta.2 is vulnerable to unrestricted file upload, where the i…EPSS 0.54%8.4CVE-2020-27613Bigbluebutton cleartext storage of sensitive data vulnerabilityThe installation procedure in BigBlueButton before 2.2.28 (or earlier) uses ClueCon as the FreeSWITCH password, which allows local users to achieve u…EPSS 0.27%7.5CVE-2025-61601Bigbluebutton vulnerabilityBigBlueButton is an open-source virtual classroom. A Denial of Service (DoS) vulnerability in versions prior to 3.0.13 allows any authenticated user …EPSS 0.47%7.5CVE-2025-61602Bigbluebutton vulnerabilityBigBlueButton is an open-source virtual classroom. A denial-of-service (DoS) vulnerability in versions prior to 3.0.13 allows any authenticated user …EPSS 0.39%7.5CVE-2022-23488Bigbluebutton information exposure vulnerabilityBigBlueButton is an open source web conferencing system. Versions prior to 2.4-rc-6 are vulnerable to Insertion of Sensitive Information Into Sent Da…EPSS 0.60%

Source: NIST National Vulnerability Database (record CVE-2026-27466), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.