What is CVE-2026-27736?

CVE-2026-27736 is a medium-severity vulnerability in Bigbluebutton, classified under URL Redirection to Untrusted Site (Open Redirect). CVSS score: 6.1/10. Published 2026-02-25.

How severe is CVE-2026-27736?

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

Open Redirect in Bigbluebutton

CVE-2026-27736

BigBlueButton is an open-source virtual classroom. In versions on the 3.x branch prior to 3.0.20, the string received with errorRedirectUrl lacks validation, using it directly in the respondWithRedirect function leads to an Open Redirect vulnerability. BigBlueButton 3.0.20 patches the issue. No known workarounds are available.

Vulnerability class: Open Redirect

EPSS: 0.001 (4.4th percentile) — read the EPSS interpretation.

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.

Affected products

Bigbluebutton — versions >= 3.0.0, < 3.0.20

Weakness classification (CWE)

CWE-601 — URL Redirection to Untrusted Site (Open Redirect)

References

security-advisories@github.com (x_refsource_CONFIRM, Patch, Vendor Advisory)
security-advisories@github.com (Patch, x_refsource_MISC)

Frequently asked questions

What is CVE-2026-27736?: CVE-2026-27736 is a medium-severity vulnerability in Bigbluebutton, classified under URL Redirection to Untrusted Site (Open Redirect). CVSS score: 6.1/10. Published 2026-02-25.
How severe is CVE-2026-27736?: Medium severity. CVSS v3 base score is 6.1 out of 10.