CVE-2022-31064 - Stored Cross-Site Scripting in BigBlueButton.

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Exploit Title: Stored Cross-Site Scripting (XSS) in BigBlueButton

Product: BigBlueButton

Vendor: BigBlueButton

Vulnerable Versions: 2.3, <2.4.8, <2.5.0

Tested Version: 2.4.7

Advisory Publication: Jun 22, 2022

Latest Update: Jun 22, 2022

Vulnerability Type: Cross-Site Scripting [CWE-79]

CVE Reference: CVE-2022-31064

CVSS Severity: High

CVSS Score: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N
Impact score: 7.2

Credit: Rick Verdoes & Danny de Weille (Hackify | pentests.nl)
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I. BACKGROUND

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BigBlueButton is an open source web conferencing system designed for online meetings and online learning. BigBlueButton is a tool used by instructors and teachers, which helps them access to Learning Management Systems, engagement tools and analytics.

II. VULNERABILITY
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Users in meetings with private chat enabled are vulnerable to a cross site scripting attack in affected versions. The attack occurs when the attacker (with a XSS payload in the name) starts a chat. in the victim's client the JavaScript will be executed. This issue has been addressed in version 2.4.8 and 2.5.0. There are no known workarounds for this issue.

III. Proof of Concept
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<img x onerror=alert()>

IV. References
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Security advisory https://pentests.nl/pentest-blog/stored-xss-in-bigbluebutton/
Patched on BigBlueButton 2.5 (https://github.com/bigbluebutton/bigbluebutton/pull/15067)
Patched on BigBlueButton 2.4 (https://github.com/bigbluebutton/bigbluebutton/pull/15090)