CVE-2026-46404

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.

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.

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.

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.

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.

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.

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.

In BigBlueButton versions prior to 3.0.13, an authenticated user can send a malformed reactionEmojiId in the GraphQL mutation chatSendMessageReaction, causing the chat functionality to crash for all meeting participants.

A Denial of Service (DoS) vulnerability in BigBlueButton versions prior to 3.0.13. An authenticated user can freeze or crash the entire server by submitting a malicious payload with a massive array in the answerIds field of the Choices response type.

In versions prior to 3.0.13, the "Shared Notes" feature in BigBlueButton contains a Stored Cross-Site Scripting (XSS) vulnerability with input in the "Username" field and output on the "Shared Notes" page when a user with a malicious username edits content. This allows a low-privileged user to execute arbitrary JavaScript in the context of higher-privileged users (e.g., Admins) who open the Shared Notes page. Version 3.0.13 fixes the issue.