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TI-2026-40046 Aliases CVE-2026-55491

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

Priority LOW 24CWE-79Published · Updated

Key facts

Attack vector
Network
Privileges required
Low
User interaction
Required
Attack complexity
Low
Impact type
Cross-site scripting
Confidentiality · integrity · availability
Low · Low · None
Fix status
Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA. Impact type from CWE-79.

Summary

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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00289 21st percentileScored 2026-11-07
Fix Fixed bigbluebutton (bigbluebutton): 3.0.29

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
No
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
bigbluebuttonbigbluebuttonbefore 3.0.293.0.29Patch availableCNA
  • bigbluebutton Vendorbigbluebutton Affected before 3.0.29 Fixed in 3.0.29 Patch available CNA

CPE names Threatist (inferred) · 1

Inferred from how NVD named this product before; not given by a source.

CPEVersionsRoleVendor
cpe:2.3:a:bigbluebutton:bigbluebutton:*:*:*:*:*:*:*:*——bigbluebutton
  • cpe:2.3:a:bigbluebutton:bigbluebutton:*:*:*:*:*:*:*:* Versions — — ·bigbluebutton

Remediation

  • Fix · CNA bigbluebutton (bigbluebutton) Fixed in 3.0.29

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-55491

References

Other 3

  • TI-2026-21873 BigBlueButton: Exposed ClamAV port enables Denial of Service CVSS 3.1HIGH 8.2
  • TI-2025-38047 BigBlueButton vulnerable to Chat DoS via invalid reactionEmojiId CVSS 3.1HIGH 7.5
  • TI-2025-38046 BigBlueButton vulnerable to DoS via PollSubmitVote GraphQL mutation CVSS 3.1HIGH 7.5
  • TI-2022-13109 Cross site scripting in username that will trigger by sending chat CVSS 3.1MEDIUM 6.5
  • TI-2020-09954 BigBlueButton before 2.2.6 allows remote attackers to read arbitrary files because the… CVSS 3.1CRITICAL 9.8
  • TI-2022-16454 BigBlueButton Greenlight Open Redirect vulnerability CVSS 3.1CRITICAL 9.1
See all 66 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences