BigBlueButton: Stored XSS in Screenshare Recording Playback via Unescaped Meeting Name

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-55491
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-08-20 22:17:22 UTC
Updated2026-08-21 16:17:19 UTC
DescriptionBigBlueButton 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.

Risk And Classification

Primary CVSS: v3.1 5.4 MEDIUM from [email protected]

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

EPSS: 0.001650000 probability, percentile 0.059470000 (date 2026-08-24)

Problem Types: CWE-79 | CWE-79 CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary5.4MEDIUMCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
3.1CNADECLARED5.4MEDIUMCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
Required
Scope
Changed
Confidentiality
Low
Integrity
Low
Availability
None

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Bigbluebutton Bigbluebutton affected < 3.0.29 Not specified

References

ReferenceSourceLinkTags
github.com/bigbluebutton/bigbluebutton/commit/a53f2b92022388bfa4109d3136... [email protected] github.com
github.com/bigbluebutton/bigbluebutton/security/advisories/GHSA-57p5-c88... [email protected] github.com
github.com/bigbluebutton/bigbluebutton/releases/tag/v3.0.29 [email protected] github.com
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