A HIGH-severity vulnerability identified as CVE-2026-27466 has been published on February 21, 2026 with a CVSS base score of 7.2. This security advisory provides a detailed breakdown of the vulnerability, its potential impact, weakness classification, and actionable steps to protect your systems.
Vulnerability Details
CVE ID: CVE-2026-27466
Severity: HIGH
CVSS Score: 7.2
Published: February 21, 2026
Weakness (CWE): CWE-668
| Attack Vector | Network |
| Attack Complexity | Low |
| Privileges Required | None |
| User Interaction | None |
| Confidentiality Impact | Low |
| Integrity Impact | None |
| Availability Impact | Low |
Technical 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.
Potential Impact
If exploited, this high-severity vulnerability could allow an attacker to cause significant damage to affected systems. Organizations running affected software should treat this as a priority remediation item.
Recommended Action
No official patch is available yet. Until one is released:
- Monitor the official NVD page and vendor channels for patch announcements.
- Restrict access to the affected system or service where possible.
- Apply network-level mitigations such as firewall rules or WAF policies.
- Enable logging and alerting for anomalous activity related to this vulnerability.
- Review your incident response plan in case of active exploitation.
References
Related Security Advisories
- [HIGH] CVE-2026-27464 — CVSS 7.7 (February 21, 2026) — HIGH / CVSS 7.7
- [HIGH] CVE-2026-26050 — CVSS 7.8 (February 20, 2026) — HIGH / CVSS 7.8
- [HIGH] CVE-2026-26205 — CVSS 7.1 — HIGH / CVSS 7.1
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