Bigbluebutton
CVE-2026-27466
HIGH
Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain
-
AccessIdentify exposed ClamAV port 3310
-
ExploitSend malicious or oversized document
-
ExecutionExhaust clamd resources
-
ImpactTrigger denial of service
Vulnerability Assessment
| Weakness |
CWE
OWASP Top 10:2025
A01:2025 - Broken Access Control
ASVS 5.0
V8 - Authorization Resource sphere isolation
MITRE ATT&CK
1 technique across 1 tactic: Collection The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up. |
| Exploitation Conditions | BigBlueButton version 3.0.21 or below with ClamAV enabled and ports 3310/7357 exposed to internet per official 'Server Customization' documentation instructions. Default installation vulnerable if ClamAV integration configured as documented. |
| Impact | CVSS 7.2 (HIGH). Attack vector: Network. Complexity: Low. Privileges required: None. User interaction: None. Exploitable via remote/network. Public exploit/POC available. |
| Exploit ScenarioDerived | A remote attacker could exploit this vulnerability to manipulate files in that folder. |
Get an e-mail when this CVE is exploited, patched or re-scored. Free account.
Alert meAnalysisAIv1 – Mar 12, 2026
BigBlueButton versions 3.0.21 and below allow remote denial of service when ClamAV is configured following official documentation, as the exposed clamd ports (3310, 7357) can be targeted by attackers to send malicious documents that exhaust server resources or crash the scanning service. This vulnerability affects Ubuntu and Docker deployments since standard firewall rules do not restrict container traffic, and public exploit code exists. An unauthenticated remote attacker requires only network access to trigger the denial of service condition.
Earlier versions of this analysis (1)
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. [CVSS 7.2 HIGH]
RemediationAI
A vendor patch is available — apply it immediately. Fixed in version 3.0.22.. Restrict network access to the affected service where possible.
Affects your stack
Find out whether the stacks and servers you run are on an affected version.
Checking this CVE against your own stacks and servers is part of the Basic plan and up.
Technical ContextAI · show details
Classified as CWE-668 (Exposure of Resource to Wrong Sphere). Affects 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 expli
Know when Bigbluebutton gets its next vulnerability
- Watch products and get an email when something new is published
- Check this CVE against your own stack and servers
- Exploit and PoC references, threat intelligence from 22 sources
No credit card · 7-day full trial
Severity by source
AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:N/A:L
Primary rating from GitHub Advisory · only source for this CVE.
CVSS VectorGitHub Advisory
Lifecycle Timeline
3DescriptionGitHub Advisory
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.
Executive ViewAI
BigBlueButton virtual classroom servers running version 3.0.21 or earlier are vulnerable to denial-of-service attacks through misconfigured ClamAV presentation file scanning, potentially disrupting remote learning and collaboration activities. Organizations using affected versions should prioritize patching to prevent service interruptions that could impact student instruction and business continuity.
Apply vendor patch. If immediate patching is not possible, temporarily disable ClamAV presentation file scanning functionality and implement file upload size restrictions at the network edge using WAF or reverse proxy rules to limit denial-of-service attack surface.
Threat Intelligence Overview
NVD
CVE.org
EPSS
GitHub
How this decision was reached
The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.
What every action level means
SSVC AssessmentENISA
Priority Score
Attack Technique
Denial of Service attacks render applications or systems unavailable by overwhelming resources or triggering failure conditions.
Affected Products (CPE)GitHub Advisory
More in Bigbluebutton
View allBigBlueButton through 2.2.28 uses Ghostscript for processing of uploaded EPS documents, and consequently may be subject
BigBlueButton before 2.2.6 allows remote attackers to read arbitrary files because the presfilename (lowercase) value ca
BigBlueButton Greenlight before 2.5.6 allows HTTP header (Host and Origin) attacks, which can result in Account Takeover
The installation procedure in BigBlueButton before 2.2.28 (or earlier) uses ClueCon as the FreeSWITCH password, which al
Denial of service in BigBlueButton versions prior to 3.0.13 lets an authenticated meeting participant freeze or crash a
Chat denial of service in BigBlueButton before 3.0.13 lets an authenticated meeting participant crash chat for every att
An issue was discovered in BigBlueButton through 2.2.29. Rated high severity (CVSS 7.5), this vulnerability is remotely
The installation procedure in BigBlueButton before 2.2.28 (or earlier) exposes certain network services to external inte
BigBlueButton before 2.2.27 has an unsafe JODConverter setting in which LibreOffice document conversions can access exte
BigBlueButton before 2.2.5 allows remote attackers to obtain sensitive files via Local File Inclusion. Rated high severi
In BigBlueButton before 2.2.28 (or earlier), the client-side Mute button only signifies that the server should stop acce
BigBlueButton before 2.3 does not implement LibreOffice sandboxing. Rated medium severity (CVSS 6.5), this vulnerability
Exploit-DB