Bigbluebutton vulnerabilities

CVE-2026-55491 Medium · 5.4 CWE-79 Aug 20, 2026

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

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.

CVE-2026-55489 Medium · 4.9 CWE-639 Aug 20, 2026

BigBlueButton: IDOR on BBB through /api/graphql via POST parameter "presentationId" leads to Authentication Bypass

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-2026-46682 High · 8.5 CWE-89 Aug 20, 2026

BigBlueButton: Blind SQL Injection AUTH (Moderator)

BigBlueButton is an open-source virtual classroom. Prior to 3.0.23, BigBlueButton allowed authenticated moderators to inject SQL through the meetingId and userId values used by refreshBreakoutRoomsVisibleForUsers in akka-bbb-apps/src/main/scala/org/bigbluebutton/core/db/BreakoutRoomUserDAO.scala. The method interpolated those values into breakout room visibility queries, allowing arbitrary SQL execution against the application database. This issue is fixed in version 3.0.23.

CVE-2026-46355 High · 7.1 CWE-287 Aug 20, 2026

BigBlueButton: Unauthenticated Session Hijack via Exposed /bigbluebutton/api/handleJoinExistingUser

BigBlueButton is an open-source virtual classroom. Prior to 3.0.23, BigBlueButton exposed /bigbluebutton/api/handleJoinExistingUser through bigbluebutton-web/grails-app/controllers/org/bigbluebutton/web/controllers/ApiController.groovy. 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 because handleJoinExistingUser was a routable controller action rather than a private helper. This issue is fixed in version 3.0.23.

CVE-2026-46404 Medium · 6.8 CWE-918 Jul 16, 2026

BigBlueButton: Presentation URL Security Hardening

BigBlueButton is an open-source virtual classroom. Prior to 3.0.23, the presentation URL validation did not properly restrict access to site local and link local addresses. The redirect following logic now pins resolved IPs. This issue is fixed in version 3.0.23.

CVE-2026-46353 High · 8.1 CWE-284 Jul 16, 2026

BigBlueButton API checksum bypass via presentationUploadExternalUrl

BigBlueButton is an open-source virtual classroom. Prior to 3.0.21, bbb-web checksum validation could be bypassed when a presentationUploadExternalUrl parameter was supplied to API request handling in CreateMeeting.java and ValidationService.java, allowing a user to send valid requests to some endpoints without a checksum. This issue is fixed in version 3.0.21.

CVE-2026-46351 High · 8.1 CWE-330 Jul 16, 2026

BigBlueButton: Insecure Randomness allows to guess user's conference session token and impersonate them

BigBlueButton is an open-source virtual classroom. Prior to 3.0.21, bbb-web generated conference sessionToken values with insufficiently secure randomness in bbb-common-web/src/main/java/org/bigbluebutton/api/Util.java and bigbluebutton-web/grails-app/controllers/org/bigbluebutton/web/controllers/ApiController.groovy, allowing a session user to predict other users' conference session tokens and impersonate them. This issue is fixed in version 3.0.21.

CVE-2026-27737 Medium · 6.5 CWE-79 May 18, 2026

BigBlueButton has Stored XSS in bbb-playback replay

BigBlueButton is an open-source virtual classroom. In versions prior to 3.0.19, the recording playback (presentation format) was not sanitizing user's input in public chat. This allowed for a malicious actor to craft and carry out a targeted XSS attack, activated on anyone replaying the recording. This issue has been fixed 3.0.19.

CVE-2026-41127 Medium · 6.5 CWE-639 Apr 21, 2026

BigBlueButton's missing authorization allows viewer to inject/overwrite captions

BigBlueButton is an open-source virtual classroom. Versions prior to 3.0.24 have a missing authorization that allows viewers to inject/overwrite captions Version 3.0.24 tightened the permissions on who is able to submit captions. No known workarounds are available.

CVE-2026-41126 Medium · 4.3 CWE-601 Apr 21, 2026

BigBlueButton has Open Redirect through bigbluebutton/api/join via get-parameter "logoutURL"

BigBlueButton is an open-source virtual classroom. Versions prior to 3.0.24 have an Open Redirect through bigbluebutton/api/join via get-parameter "logoutURL." Version 3.0.24 has adjusted the handling of requests with incorrect checksum so that the default logoutURL is used. No known workarounds are available.

CVE-2026-27736 Medium · 6.1 CWE-601 Feb 25, 2026

BigBlueButton has Open Redirect vulnerability in ApiController

BigBlueButton is an open-source virtual classroom. In versions on the 3.x branch prior to 3.0.20, the string received with errorRedirectUrl lacks validation, using it directly in the respondWithRedirect function leads to an Open Redirect vulnerability. BigBlueButton 3.0.20 patches the issue. No known workarounds are available.

CVE-2026-27467 Low · 2.4 CWE-200 Feb 21, 2026

BigBlueButton: Audio from participants to the server initially unmuted

BigBlueButton is an open-source virtual classroom. In versions 3.0.19 and below, when first joining a session with the microphone muted, the client sends audio to the server regardless of mute state. Media is discarded at the server side, so it isn't audible to any participants, but this may allow for malicious server operators to access audio data. The behavior is only incorrect between joining the meeting and the first time the user unmutes. This issue has been fixed in version 3.0.20.

CVE-2026-27466 High · 8.2 CWE-668 Feb 21, 2026

BigBlueButton: Exposed ClamAV port enables Denial of Service

BigBlueButton is an open-source virtual classroom. In versions 3.0.21 and below, the official documentation for "Server Customization" on Support for ClamAV as presentation file scanner contains instructions that leave a BBB server vulnerable for Denial of Service. The flawed command exposes both ports (3310 and 7357) to the internet. A remote attacker can use this to send complex or large documents to clamd and waste server resources, or shutdown the clamd process. The clamd documentation explicitly warns about exposing this port. Enabling ufw (ubuntu firewall) during install does not help, because Docker routes container traffic through the nat table, which is not managed or restricted by ufw. Rules installed by ufw in the filter table have no effect on docker traffic. In addition, the provided example also mounts /var/bigbluebutton with write permissions into the container, which should not be required. Future vulnerabilities in clamd may allow attackers to manipulate files in that folder. Users are unaffected unless they have opted in to follow the extra instructions from BigBlueButton's documentation. This issue has been fixed in version 3.0.22.