XSS in Bigbluebutton Bbb-Playback
CVE-2026-27737
BigBlueButton is an open-source virtual classroom. In versions prior to 3.0.19, the recording playback (presentation format) was not sanitizing user's input in public chat. This allowed for a malicious actor to craft and carry out a targeted XSS attack, activated on anyone replaying the recording. This issue has been fixed 3.0.19.
Vulnerability class: XSS (Cross-Site Scripting)
Published · last modified .
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:N/I:H/A:N.
EPSS exploit prediction
EPSS: 0.004 (34.6th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 35th percentile — 34.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.003 · newest: 0.004 · change: +0.002
Affected products
- Bigbluebutton Bbb-Playback — versions < 5.4.3
- Bigbluebutton — versions < 3.0.19
- Blindsidenetworks Scalite — versions < 1.7.0
Weakness classification (CWE)
References
- github.com/bigbluebutton/bigbluebutton/security/advisories/GHSA-8vv7-vj94-q2pv
- github.com/bigbluebutton/bbb-playback/commit/09e89bfe4ff8488b68c3ff040d3081e419…
- github.com/bigbluebutton/bigbluebutton/commit/69f45aa1b963dc7d80179d0155acc670a…
- github.com/bigbluebutton/bigbluebutton/releases/tag/v3.0.19
- github.com/blindsidenetworks/scalelite/releases/tag/v1.7.0
Frequently asked questions
- What is CVE-2026-27737?
- CVE-2026-27737 is a medium-severity vulnerability in Bigbluebutton Bbb-Playback, classified under Cross-site Scripting. CVSS score: 6.5/10. Published 2026-05-18.
- How severe is CVE-2026-27737?
- Medium severity. CVSS v3 base score is 6.5 out of 10.