CVE-2025-25279
📋 TL;DR
This vulnerability in Mattermost Boards allows attackers to read arbitrary files on the server by importing specially crafted board archives. It affects Mattermost instances running vulnerable versions of the Boards feature, potentially exposing sensitive system files and configuration data.
💻 Affected Systems
- Mattermost Boards
📦 What is this software?
Mattermost Server by Mattermost
Mattermost Server by Mattermost
Mattermost Server by Mattermost
Mattermost Server by Mattermost
⚠️ Risk & Real-World Impact
Worst Case
Complete server compromise through reading sensitive files like /etc/passwd, SSH keys, database credentials, or configuration files containing secrets.
Likely Case
Exfiltration of sensitive configuration data, environment variables, or credentials stored in accessible files on the server.
If Mitigated
Limited impact if proper network segmentation, file system permissions, and access controls prevent unauthorized board imports.
🎯 Exploit Status
Exploitation requires authenticated access with board import permissions. The path traversal technique is well-understood and easy to weaponize once details are known.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Mattermost versions 10.4.2, 9.11.8, 10.3.3, 10.2.3 and later
Vendor Advisory: https://mattermost.com/security-updates
Restart Required: Yes
Instructions:
1. Backup your Mattermost instance. 2. Upgrade to patched version using your deployment method (Docker, binary, package manager). 3. Restart the Mattermost service. 4. Verify the upgrade completed successfully.
🔧 Temporary Workarounds
Disable Board Import Feature
allTemporarily disable board import functionality to prevent exploitation while planning upgrade.
# Modify Mattermost config.json to restrict board imports
# Set "EnableBoardImport": false in config or via System Console
Restrict Board Permissions
allLimit board import/export permissions to trusted administrators only.
# Use System Console → User Management → Permissions
# Remove board import permissions from non-admin users
🧯 If You Can't Patch
- Implement strict network segmentation to isolate Mattermost servers from sensitive systems
- Apply strict file system permissions to limit Mattermost process access to only necessary directories
🔍 How to Verify
Check if Vulnerable:
Check Mattermost version via System Console → About or run: grep -i version /opt/mattermost/config/config.jsonCheck Version:
cat /opt/mattermost/config/config.json | grep -i versionVerify Fix Applied:
Confirm version is 10.4.2+, 9.11.8+, 10.3.3+, or 10.2.3+ and test board import functionality with safe test data.📡 Detection & Monitoring
Log Indicators:
- Unusual board import activity from non-admin users
- Multiple failed import attempts with suspicious file paths
- Access to system files via board export functionality
Network Indicators:
- Large board export files containing unexpected data
- Unusual patterns in board import API calls
SIEM Query:
source="mattermost" ("board import" OR "board export") AND (path=".." OR path="/etc" OR path="/root")