Quick answers
- Is CVE-2026-55491 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-55491 being exploited in the wild.
- How severe is CVE-2026-55491?
- Medium severity, with a CVSS score of 5.4, published 20 August 2026.
- Which products and versions are affected?
- BigBlueButton prior to 3.0.29.
- Is there a fix for CVE-2026-55491?
- A patch was published on 2026-06-12: Fixed in version 3.0.29 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
- How is CVE-2026-55491 attacked?
- It is attacked over the network, in a web application.
- Am I affected by CVE-2026-55491?
- Check whether you run BigBlueButton at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
Technical details
This is a stored cross-site scripting (XSS) vulnerability in the screenshare playback template (record-and-playback/screenshare/playback/index.html.erb). The meetingName parameter was not properly HTML-escaped before being rendered in the playback page. A low-privileged user could create a meeting with a malicious script embedded in the meeting name; when another user later replayed the recording, the script would execute in their browser with their privileges. The fix involved escaping meetingName using CGI.escapeHTML in the ERB template. The vulnerability is present in all versions prior to 3.0.29 and is fixed in 3.0.29.
Affected products
- BigBlueButton BigBlueButton prior to 3.0.29
Timeline
- 2026-06-12: disclosed
- 2026-06-12: patched: Fixed in version 3.0.29
- 2026-08-20: advisory