Mattermost is a popular open-source, self-hosted messaging platform that provides secure, private messaging for organizations. The platform aims to provide an enterprise-grade messaging service with various security features such as two-factor authentication (2FA) or multi-factor authentication (MFA).

However, it has been recently discovered that a security vulnerability exists in Mattermost version 10.4.x <= 10.4.2, 10.3.x <= 10.3.3, 9.11.x <= 9.11.8, and 10.5.x <= 10.5.. This vulnerability, dubbed CVE-2025-25068, involves a failure to enforce MFA on plugin endpoints. As a result, authenticated attackers can exploit this vulnerability to bypass MFA protection by sending API requests to plugin-specific routes.

In this post, we will explore the technical details of the CVE-2025-25068 vulnerability, demonstrate how it can be exploited, and provide links to original references. The aim is to raise awareness about this security issue and help organizations protect their Mattermost installations.

CVE-2025-25068: Technical Details

Mattermost plugins usually expose custom API endpoints, which can be accessed by sending requests to specific routes. These plugin endpoints are supposed to be protected by the same authentication and authorization mechanisms used by core Mattermost API endpoints, including MFA.

However, in the affected versions of Mattermost, the enforcement of MFA protection is not consistent across plugin endpoints. While the core API endpoints are protected by MFA, some plugin-specific routes may allow authenticated users to access sensitive data or perform critical actions without presenting their second authentication factor.

This inconsistency is due to a design flaw in the Mattermost server's api4 package, which is responsible for handling API requests and applying security controls. The api4 package does not correctly apply MFA checks to plugin routes, allowing attackers with valid session tokens to bypass MFA and interact with affected plugins.

To exploit this vulnerability, an attacker needs to

1. Obtain the session token of a target Mattermost user with MFA enabled. This can be achieved through various methods, such as social engineering, phishing, or exploiting other vulnerabilities in the system.
2. Identify the plugin-specific routes that are not protected by MFA. This can involve reviewing the API documentation of installed plugins or analyzing data obtained from the get_plugins API endpoint.

Here's an example of a malicious API request that exploits the CVE-2025-25068 vulnerability

import requests

url = "https://your-mattermost-server_url/api/v4/plugins/your-plugin-id/your-vulnerable-route";
session_token = "your_obtained_session_token"
headers = {
    "Authorization": f"Bearer {session_token}"
}

response = requests.get(url, headers=headers)

if response.status_code == 200:
    print("Successfully bypassed MFA and accessed the plugin route.")
else:
    print("Failed to access the plugin route.")

Original References

The CVE-2025-25068 vulnerability has been reported and acknowledged by the Mattermost team. For more information, please refer to the following sources:

- CVE-2025-25068 - NVD Detail
- Mattermost Security Updates - Mattermost Blog

Conclusion

CVE-2025-25068 is a critical security vulnerability that impacts several Mattermost versions and exposes organizations to the risk of bypassing MFA protections. Organizations using Mattermost should assess their exposure to this vulnerability and apply the necessary security updates or mitigation measures. Regularly reviewing and updating your organization's security posture can help prevent potential security breaches and protect your valuable data and assets.

Timeline

Published on: 03/21/2025 09:15:12 UTC
Last modified on: 03/27/2025 14:03:38 UTC