CVE-2026-55491CWE-79cross-site-scripting

CVE-2026-55491

Medium · published August 21, 2026

CVSS v3.1
5.4
EPSS
0%
Percentile
20.3
In the wild
Unconfirmed
What it is

BigBlueButton is an open-source virtual classroom. Prior to 3.0.29, BigBlueButton failed to escape meetingName in record-and-playback/screenshare/playback/index.html.erb when generating the screenshare playback format. A low-privileged user could store a crafted meeting name that embedded script content, and the script executed in another user's browser when that user replayed the recording. This issue is fixed in version 3.0.29.

The record
Technical detail
CVSS v3.1
5.4 · MEDIUM
Vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
CVSS v4.0
Not supplied
EPSS
0.00289 · 20.3th percentile
Weakness
CWE-79 · Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Published
2026-08-21T02:17Z
References (3)
https://github.com/bigbluebutton/bigbluebutton/commit/a53f2b92022388bfa4109d3136d1f3a932404b1b · [email protected]https://github.com/bigbluebutton/bigbluebutton/releases/tag/v3.0.29 · [email protected]https://github.com/bigbluebutton/bigbluebutton/security/advisories/GHSA-57p5-c888-74f9 · [email protected]
EPSS history
Timeline
  • 20 AUG 21:35Z
    BigBlueButton: Stored XSS in Screenshare Recording Playback via Unescaped Meeting Name
    cvelistv5