In this long-read blog post, we would like to introduce a previously unknown security vulnerability involving the Mattermost Desktop App, specifically for macOS users. With the vulnerability identified as CVE-2025-1398, the app can pose a significant risk to user privacy and security if exploited successfully. By highlighting this vulnerability, our goal is to raise awareness and provide a comprehensive guide to understanding, analyzing, and ultimately mitigating its adverse effects.

Background

Mattermost is an open-source and self-hosted team collaboration platform, often utilized as an alternative to popular instant messaging platforms like Slack and Microsoft Teams. The desktop app version is available to users running macOS, Windows, or Linux. Recently, it has come to light that the app contains a critical security vulnerability in versions <=5.10. - specifically on macOS.

Upon a thorough analysis, it was discovered that the Mattermost Desktop App explicitly declared unnecessary macOS entitlements, potentially allowing an attacker with remote access to exploit this vulnerability and bypass macOS's built-in privacy and security features, collectively referred to as Transparency, Consent, and Control (TCC).

Exploit Details

Affected Product: Mattermost Desktop App
Affected Version: <=5.10.
Platform: macOS
CVE ID: CVE-2025-1398

By leveraging these unnecessary macOS entitlements, an attacker can inject malicious code remotely to bypass the TCC. This can result in unauthorized access to sensitive data - including, but not limited to - contacts, calendar events, location information, and other file systems.

Upon investigation, the code snipplet in question within the app consists of the following unintended entitlements:

<key>com.apple.security.device.microphone</key>
<true/>
<key>com.apple.security.device.camera</key>
<true/>
<key>com.apple.security.personal-information.addressbook</key>
<true=""/>
<key>com.apple.security.personal-information.calendars</key>
<true/>

These entitlements essentially grant the app access to critical user data like the microphone, camera, address book, and calendar information without the user's explicit consent.

To make matters worse, attackers can exploit these entitlements remotely. With sufficient know-how, code injection techniques could enable a malicious entity to initiate a code execution attack and access sensitive user data.

It is worth noting that the Mattermost Desktop App doesn't require access to any of these functionalities to operate correctly. As such, these entitlements are superfluous and pose an unnecessary security risk.

Original References

For more in-depth information on the Mattermost Desktop App vulnerability, consult the following resources:

1. Mattermost's official security advisory warning: Official Advisory
2. An in-depth technical blog post detailing the vulnerability: Technical Background
3. A detailed explanation of macOS's TCC mechanism: TCC Overview

Mitigation

The good news is that this vulnerability has been addressed and fixed in Mattermost Desktop App v 5.10.1. Thus, the best course of action involves upgrading to the latest version of the app to mitigate any risks associated with CVE-2025-1398. Users are strongly advised to update their Mattermost Desktop App installations at the earliest opportunity, ensuring that they are protected from this potentially malicious security exploit.

Conclusion

While discovering and discussing security vulnerabilities can be cause for concern, they also serve as critical reminders to the importance of vigilance in today's interconnected digital landscape. By keeping app installations updated, staying informed on the latest security advisories, and proactively addressing security issues when they arise, users can help protect their sensitive data and maintain the privacy and security they value in a rapidly evolving technological landscape.

Stay safe and informed, and always keep your software up to date!

Timeline

Published on: 03/17/2025 15:15:43 UTC
Last modified on: 03/31/2025 16:15:22 UTC