What is CVE-2020-27608?

CVE-2020-27608 is a medium-severity vulnerability in Bigbluebutton, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2020-10-21.

How severe is CVE-2020-27608?

Medium severity. CVSS v3 base score is 6.1 out of 10.

XSS in Bigbluebutton

CVE-2020-27608

In BigBlueButton before 2.2.28 (or earlier), uploaded presentations are sent to clients without a Content-Type header, which allows XSS, as demonstrated by a .png file extension for an HTML document.

Vulnerability class: XSS (Cross-Site Scripting)

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

CVSS v3 metric

CVSS v3 base score 6.1 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N.

EPSS exploit prediction

EPSS: 0.008 (55.5th percentile), scored 2026-09-29.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 55th percentile — 55.5% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.008 · newest: 0.008 · change: 0.000

Affected products

Bigbluebutton

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

References

www.golem.de/news/big-blue-button-das-grosse-blaue-sicherheitsrisiko-2010-15161… (Exploit, Third Party Advisory)

Frequently asked questions

What is CVE-2020-27608?: CVE-2020-27608 is a medium-severity vulnerability in Bigbluebutton, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2020-10-21.
How severe is CVE-2020-27608?: Medium severity. CVSS v3 base score is 6.1 out of 10.