Auth bypass in Bigbluebutton

CVE-2026-55489

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.

Vulnerability class: IDOR (Insecure Direct Object Reference)

Published · last modified .

CVSS v3 metric

CVSS v3 base score 4.9 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:N/I:L/A:L.

EPSS exploit prediction

EPSS: 0.003 (21.8th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 22nd percentile — 21.8% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-55489: held from 0.002 to 0.003.

EPSS over last 30 days · oldest: 0.002 · newest: 0.003 · change: +0.001

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-55489?
CVE-2026-55489 is a medium-severity vulnerability in Bigbluebutton, classified under Authorization Bypass Through User-Controlled Key. CVSS score: 4.9/10. Published 2026-08-20.
How severe is CVE-2026-55489?
Medium severity. CVSS v3 base score is 4.9 out of 10.