CVE-2026-27466Public exploitNetwork attack vector

Unauthenticated service interruption via exposed clamd port

Published Feb 21, 2026 · Updated Feb 21, 2026

Denial of service in BigBlueButton 3.0.21 and earlier allows remote attackers to stop ClamAV scanning through an exposed clamd port. The documented Docker command publishes ports 3310 and 7357 on every interface, bypassing UFW filtering, so clamd accepts unauthenticated SHUTDOWN commands or resource-intensive documents. Exposure exists only on servers whose operators followed the optional ClamAV customization instructions; the result is clamd shutdown or CPU and memory exhaustion that interrupts presentation scanning.

CVSS severity8.2
High
EPSS probability0.40%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in BigBlueButton 3.0.21 and earlier allows remote attackers to stop ClamAV scanning through an exposed clamd port. The documented Docker command publishes ports 3310 and 7357 on every interface, bypassing UFW filtering, so clamd accepts unauthenticated SHUTDOWN commands or resource-intensive documents. Exposure exists only on servers whose operators followed the optional ClamAV customization instructions; the result is clamd shutdown or CPU and memory exhaustion that interrupts presentation scanning.

The record

CVE
CVE-2026-27466
Published
Feb 21, 2026
Updated
Feb 21, 2026
Vendor
BigBlueButton Inc.
Product
BigBlueButton
Classifications
CWE-668, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 21, 2026CVE publishedPublication date reported by the CVE source.
  2. Feb 21, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 3.0.22

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

BigBlueButton Inc. · BigBlueButtonversion=< 3.0.22

Published CVSS scores

7.2GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:N/A:L
8.2NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-668Exposure of Resource to Wrong Sphere
T1499.004Endpoint Denial of Service: Application or System Exploitation

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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