Overview
CVE-2025-12756 is a medium severity vulnerability affecting Mattermost versions 11.0.x <= 11.0.2, 10.12.x <= 10.12.1, 10.11.x <= 10.11.4, and 10.5.x <= 10.5.12. This vulnerability exposes a flaw in the user permission validation within the Boards feature, specifically related to comment deletion. Authenticated users with the editor role can exploit this to delete comments created by other users, which they are not authorized to do.
Technical Details
The vulnerability stems from a lack of proper permission validation before allowing a user to delete a comment in Mattermost Boards. Specifically, the system does not adequately verify if the user attempting to delete a comment is the original author or has sufficient administrative privileges to perform the deletion. This oversight allows an authenticated user holding the ‘editor’ role to delete comments regardless of authorship. The affected endpoints related to comment deletion lack necessary checks on user roles and comment ownership. This creates a security gap that allows unauthorized modification of board content.
CVSS Analysis
The Common Vulnerability Scoring System (CVSS) score for CVE-2025-12756 is 4.3 (MEDIUM).
- Attack Vector: Network
- Attack Complexity: Low
- Privileges Required: Low
- User Interaction: None
- Scope: Unchanged
- Confidentiality Impact: None
- Integrity Impact: Low
- Availability Impact: None
The CVSS score reflects the relatively low impact of the vulnerability, as it primarily affects data integrity within the Boards feature. While potentially disruptive, it does not directly expose sensitive information or cause significant system downtime.
Possible Impact
The unauthorized deletion of comments can lead to several negative consequences:
- Data Loss: Important information or discussions within Boards can be permanently deleted.
- Workflow Disruption: Collaboration and project tracking can be hindered if comments are removed without authorization.
- Reduced Trust: Users may lose confidence in the platform if they are concerned about the integrity of their contributions.
- Compliance Issues: If Boards are used for compliance-related documentation, unauthorized deletion could lead to regulatory issues.
Mitigation and Patch Steps
To mitigate the risk posed by CVE-2025-12756, it is strongly recommended to upgrade your Mattermost instance to a patched version. Upgrade to:
- Mattermost 11.1.0 or later (for 11.0.x series)
- Mattermost 10.13.0 or later (for 10.12.x series)
- Mattermost 10.11.5 or later (for 10.11.x series)
- Mattermost 10.5.13 or later (for 10.5.x series)
Instructions for upgrading Mattermost can be found on the official Mattermost documentation site. Apply the patch as soon as possible to protect your instance.
