What is CVE-2020-27604?

CVE-2020-27604 is a medium-severity vulnerability in Bigbluebutton, classified under Improper Encoding or Escaping of Output. CVSS score: 6.5/10. Published 2020-10-21.

How severe is CVE-2020-27604?

Medium severity. CVSS v3 base score is 6.5 out of 10.

Vulnerability in Bigbluebutton

CVE-2020-27604

BigBlueButton before 2.3 does not implement LibreOffice sandboxing. This might make it easier for remote authenticated users to read the API shared secret in the bigbluebutton.properties file. With the API shared secret, an attacker can (for example) use api/join to join an arbitrary meeting regardless of its guestPolicy setting.

Published 2020-10-21 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N.

EPSS exploit prediction

EPSS: 0.011 (65.5th percentile), scored 2026-09-29.

Low probability of exploitation in the next 30 days, but still tracked. 65th percentile — 65.5% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.011 · newest: 0.011 · change: 0.000

Affected products

Bigbluebutton

Weakness classification (CWE)

CWE-116 — Improper Encoding or Escaping of Output

References

www.golem.de/news/big-blue-button-das-grosse-blaue-sicherheitsrisiko-2010-15161… (Exploit, Third Party Advisory)
docs.bigbluebutton.org/dev/api.html (Product)

Frequently asked questions

What is CVE-2020-27604?: CVE-2020-27604 is a medium-severity vulnerability in Bigbluebutton, classified under Improper Encoding or Escaping of Output. CVSS score: 6.5/10. Published 2020-10-21.
How severe is CVE-2020-27604?: Medium severity. CVSS v3 base score is 6.5 out of 10.