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CVE-2026-27466— BigBlueButton: Exposed ClamAV port enables Denial of Service

Quick assessment

Affected
bigbluebutton bigbluebutton
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

BigBlueButton是BigBlueButton社区的一套开源的Web会议系统。 BigBlueButton 3.0.21及之前版本存在安全漏洞，该漏洞源于官方文档中ClamAV配置指令不当，可能导致远程攻击者发起拒绝服务攻击。

CVSS 7.2 · High EPSS 0.58% · P46

Possible ATT&CK Techniques 1 AI

T1496 · Resource Hijacking
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I. Basic Information for CVE-2026-27466

Vulnerability Information
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Vulnerability Title
BigBlueButton: Exposed ClamAV port enables Denial of Service
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:N/A:L
Source: CVE Program / CVE List V5
Vulnerability Type
将资源暴露给错误范围
Source: CVE Program / CVE List V5
Vulnerability Title
BigBlueButton 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
BigBlueButton是BigBlueButton社区的一套开源的Web会议系统。 BigBlueButton 3.0.21及之前版本存在安全漏洞，该漏洞源于官方文档中ClamAV配置指令不当，可能导致远程攻击者发起拒绝服务攻击。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
bigbluebutton bigbluebutton < 3.0.22 -

II. Public POCs for CVE-2026-27466

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III. Intelligence Information for CVE-2026-27466

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IV. Related Vulnerabilities

Same product: bigbluebutton
Same vendor: bigbluebutton
Same weakness: CWE-668

V. Comments for CVE-2026-27466

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