Overview
CVE-2025-55070 is a medium severity security vulnerability affecting Mattermost versions prior to version 11. This vulnerability allows unauthenticated users to access sensitive information through WebSocket events due to a failure to enforce multi-factor authentication (MFA) on WebSocket connections.
Technical Details
The vulnerability arises because Mattermost versions before 11 do not properly enforce MFA requirements on WebSocket connections. WebSocket connections are persistent communication channels between the client and the server, used for real-time updates and event notifications. By bypassing MFA enforcement on these connections, an attacker can potentially subscribe to and receive sensitive data streamed through WebSocket events without authenticating.
Specifically, the server does not check if a WebSocket connection has been established following successful MFA authentication. This omission enables an attacker to potentially establish a WebSocket connection and gain access to sensitive information without valid credentials, effectively bypassing the intended security controls.
CVSS Analysis
The Common Vulnerability Scoring System (CVSS) score for CVE-2025-55070 is 6.5 (Medium).
This score is based on the following factors:
- Attack Vector (AV): Network (N)
- Attack Complexity (AC): Low (L)
- Privileges Required (PR): None (N)
- User Interaction (UI): None (N)
- Scope (S): Unchanged (U)
- Confidentiality Impact (C): High (H)
- Integrity Impact (I): None (N)
- Availability Impact (A): None (N)
Possible Impact
A successful exploit of CVE-2025-55070 could have significant consequences, including:
- Data Breach: Exposure of sensitive information such as messages, user data, and configuration details.
- Unauthorized Access: An attacker could potentially monitor real-time communications and gain insights into organizational activities.
- Reputational Damage: A breach resulting from this vulnerability could damage the organization’s reputation and erode user trust.
Mitigation and Patch Steps
The recommended mitigation is to upgrade your Mattermost instance to version 11 or later. This version includes the necessary security fix to enforce MFA on WebSocket connections.
- Backup Your Data: Before upgrading, ensure you have a recent backup of your Mattermost data.
- Review Release Notes: Carefully review the release notes for version 11 to understand any potential compatibility issues or required configuration changes.
- Upgrade Mattermost: Follow the official Mattermost upgrade instructions for your deployment environment.
- Verify MFA Enforcement: After the upgrade, verify that MFA is properly enforced on WebSocket connections by testing the functionality.
