What’s Vulnerable › Vulnerabilities

CVE-2026-27467: BigBlueButton: Audio from participants to the server initially unmuted

• Severity: low (CVSS 2.4 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-02-21 · updated 2026-06-17
• Weakness: CWE-200

Description

BigBlueButton is an open-source virtual classroom. In versions 3.0.19 and below, when first joining a session with the microphone muted, the client sends audio to the server regardless of mute state. Media is discarded at the server side, so it isn't audible to any participants, but this may allow for malicious server operators to access audio data. The behavior is only incorrect between joining the meeting and the first time the user unmutes. This issue has been fixed in version 3.0.20.

Affected products

• bigbluebutton: before 3.0.20 — fixed in 3.0.20

How to fix

Upgrade to a fixed version: bigbluebutton 3.0.20. Check the vendor advisory for mitigations.

References

• https://github.com/bigbluebutton/bigbluebutton/commit/3aa47832bc2b17178799bd932453c226e8f95703
• https://github.com/bigbluebutton/bigbluebutton/security/advisories/GHSA-6gj9-5rhm-68j8

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