BigBlueButton up to 3.0.19 respondWithRedirect redirect

Summaryinfo

A vulnerability has been found in BigBlueButton up to 3.0.19 and classified as problematic. Affected is the function respondWithRedirect. The manipulation leads to redirect. This vulnerability is traded as CVE-2026-27736. It is possible to initiate the attack remotely. There is no exploit available. The affected component should be upgraded.

Detailsinfo

A vulnerability was found in BigBlueButton up to 3.0.19 and classified as problematic. This issue affects the function respondWithRedirect. The manipulation with an unknown input leads to a redirect vulnerability. Using CWE to declare the problem leads to CWE-601. A web application accepts a user-controlled input that specifies a link to an external site, and uses that link in a Redirect. This simplifies phishing attacks. Impacted is integrity. The summary by CVE is:

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.

It is possible to read the advisory at github.com. The identification of this vulnerability is CVE-2026-27736 since 02/23/2026. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. It demands that the victim is doing some kind of user interaction. Technical details of the vulnerability are known, but there is no available exploit. The attack technique deployed by this issue is T1204.001 according to MITRE ATT&CK.

Upgrading to version 3.0.20 eliminates this vulnerability. Applying the patch 691f92f3af0d6b796b91cb968977068663119812 is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the vulnerability database at CERT Bund (WID-SEC-2026-0488). Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Affected

• Open Source BigBlueButton

Productinfo

Name

• BigBlueButton

Version

• 3.0.0
• 3.0.1
• 3.0.2
• 3.0.3
• 3.0.4
• 3.0.5
• 3.0.6
• 3.0.7
• 3.0.8
• 3.0.9
• 3.0.10
• 3.0.11
• 3.0.12
• 3.0.13
• 3.0.14
• 3.0.15
• 3.0.16
• 3.0.17
• 3.0.18
• 3.0.19

License

• free

Website

• Product: https://github.com/bigbluebutton/bigbluebutton/

CPE 2.3info

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CPE 2.2info

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Entryinfo

Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

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