Description
BigBlueButton is an open-source virtual classroom. A denial-of-service (DoS) vulnerability in versions prior to 3.0.13 allows any authenticated user to crash the chat functionality for all participants in a meeting by sending a malformed `reactionEmojiId` in the GraphQL mutation `chatSendMessageReaction`. Version 3.0.13 contains a patch. No known workarounds are available.
Affected products
bigbluebutton: bigbluebutton
References3
- github.com/bigbluebutton/bigbluebutton/security/advisories/GHSA… ExploitVendor Advisory
- github.com/bigbluebutton/bigbluebutton/security/advisories/GHSA… ExploitVendor Advisory
- github.com/bigbluebutton/bigbluebutton/pull/23651 Issue TrackingPatch
Metrics
- CVSS 3.1
-
7.5
HIGH
Score source: CNA
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - EPSS — exploit probability
- 0% percentile: 34 · as of 9 November 2026
- CWE
- CWE-703
Could this be exploited in your environment?
A patch closes the known hole. A penetration test shows what an attacker can still reach — with proof.