CVE-2026-55491
MediumCVSS 5.4Exploitation Probability (EPSS)
Low risk6th percentile - higher than 6% of all known CVEs
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.
Risk Assessment
The vulnerability enables XSS (Cross-Site Scripting), which can lead to session theft, account takeover, or unauthorized actions in the victim's context. Requires user interaction (replaying the recording).
Recommendation
Update BigBlueButton to version 3.0.29 or later. Additionally, consider filtering meeting names at the application level.
Other vulnerabilities in BigBlueButton
See all- CVE-2026-55489Medium
BigBlueButton is an open-source virtual classroom. Prior to 3.0.29, BigBlueButton presenters could submit a presentationId through /api/graphql that identified a presentation belonging to another meeting. akka-bbb-apps/src/main/scala/org/bigbluebutton/core/apps/presentationpod/RemovePresentationPubMsgHdlr.scala did not verify the presentation's meeting identifier before deletion, allowing a presenter who knew the identifier to delete another meeting's presentation and disrupt its availability. This issue is fixed in version 3.0.29.
- CVE-2026-46682High
BigBlueButton before version 3.0.23 allows authenticated moderators to inject SQL through the meetingId and userId values used by refreshBreakoutRoomsVisibleForUsers. The method interpolates these values into breakout room visibility queries, allowing arbitrary SQL execution against the application database. This issue is fixed in version 3.0.23.
- CVE-2026-46355High
BigBlueButton before version 3.0.23 exposed /bigbluebutton/api/handleJoinExistingUser, which was a routable controller action rather than a private helper. A requester able to supply an existingUserID for an active participant could reuse that participant's session and impersonate the participant in the same meeting. This issue is fixed in version 3.0.23.
- CVE-2026-46404Medium
BigBlueButton prior to version 3.0.23 improperly restricted access to local network addresses during presentation URL validation. The redirect following logic has been fixed to block local IP ranges.
- CVE-2026-46353High
In BigBlueButton prior to version 3.0.21, a vulnerability was found where checksum validation could be bypassed when a presentationUploadExternalUrl parameter was supplied to API request handling. This allows a user to send valid requests to some endpoints without a checksum.
- CVE-2026-46351High
BigBlueButton prior to version 3.0.21 generated conference session tokens with insufficiently secure randomness, allowing a session user to predict other users' tokens and impersonate them.
- CVE-2026-27737Medium
BigBlueButton prior to version 3.0.19 does not sanitize user input in public chat during recording playback. This allows a malicious actor to carry out an XSS attack that activates on anyone replaying the recording. The issue has been fixed in version 3.0.19.
- CVE-2023-33176Medium
BigBlueButton, an open-source virtual classroom, has a Server-Side Request Forgery (SSRF) vulnerability in affected versions that allows users to supply a URL for downloading presentations without prior validation. An update to the `followRedirect` method has been made to validate all URLs used for presentation downloads.
Original NVD description (English source)
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.