CVE-2025-61602: BigBlueButton vulnerable to Chat DoS via invalid reactionEmojiId

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2025-10-09 · updated 2026-10-19
Weakness: CWE-703

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: before 3.0.13 — fixed in 3.0.13

How to fix

Upgrade to a fixed version: bigbluebutton 3.0.13. Check the vendor advisory for mitigations.

References

https://github.com/bigbluebutton/bigbluebutton/pull/23651
https://github.com/bigbluebutton/bigbluebutton/security/advisories/GHSA-45j2-m26c-3pcm
https://github.com/bigbluebutton/bigbluebutton/security/advisories/GHSA-45j2-m26c-3pcm

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