What’s Vulnerable › Vulnerabilities

CVE-2026-55491: BigBlueButton: Stored XSS in Screenshare Recording Playback via Unescaped Meeting Name

• Severity: medium (CVSS 5.4 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-08-20 · updated 2026-10-26
• Weakness: CWE-79

Description

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.

Affected products

• bigbluebutton: before 3.0.29

References

• https://github.com/bigbluebutton/bigbluebutton/commit/a53f2b92022388bfa4109d3136d1f3a932404b1b
• https://github.com/bigbluebutton/bigbluebutton/releases/tag/v3.0.29
• https://github.com/bigbluebutton/bigbluebutton/security/advisories/GHSA-57p5-c888-74f9

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