Medium severity · published May 18, 2026
CVE-2026-27737
BigBlueButton has Stored XSS in bbb-playback replay
6.5
CVSS
0.3%
EPSS
No
On KEV
Description
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
None
Confidentiality
None
Integrity
High
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.3% · higher than 17% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
BB
bbb-playback · bigbluebutton
< 5.4.3 · source: vendor
BI
bigbluebutton · bigbluebutton
< 3.0.19 · source: vendor
SC
scalite · blindsidenetworks
< 1.7.0 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-27737
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-27737
github.com
https://github.com/bigbluebutton/bbb-playback/commit/09e89bfe4ff8488b68c3ff040d3081e419dc89b1
github.com
https://github.com/bigbluebutton/bigbluebutton/commit/69f45aa1b963dc7d80179d0155acc670aec5c4fc
github.com
https://github.com/bigbluebutton/bigbluebutton/releases/tag/v3.0.19
github.com
https://github.com/bigbluebutton/bigbluebutton/security/advisories/GHSA-8vv7-vj94-q2pv
github.com
https://github.com/blindsidenetworks/scalelite/releases/tag/v1.7.0