CVE-2026-27736: BigBlueButton has Open Redirect vulnerability in ApiController

Severity: medium (CVSS 6.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-02-25 · updated 2026-06-17
Weakness: CWE-601

Description

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.

Affected products

bigbluebutton: before 3.0.20 — fixed in 3.0.20

How to fix

Upgrade to a fixed version: bigbluebutton 3.0.20. Check the vendor advisory for mitigations.

References

https://github.com/bigbluebutton/bigbluebutton/commit/691f92f3af0d6b796b91cb968977068663119812
https://github.com/bigbluebutton/bigbluebutton/security/advisories/GHSA-65cv-rg9f-qqrx

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