CVE-2025-6233
📋 TL;DR
This vulnerability allows system administrators in Mattermost to read arbitrary files on the server through path traversal in bulk import JSONL files. Attackers can exploit this by crafting malicious file attachment paths to access sensitive system files. Only Mattermost instances with vulnerable versions are affected.
💻 Affected Systems
- Mattermost
📦 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
A compromised or malicious system administrator could read sensitive system files like /etc/passwd, configuration files, or SSH keys, potentially leading to full server compromise.
Likely Case
An attacker with admin privileges could read sensitive configuration files or application data, enabling further attacks or data exfiltration.
If Mitigated
With proper access controls and monitoring, impact is limited to unauthorized file reads by privileged users, which can be detected and contained.
🎯 Exploit Status
Exploitation requires admin access to the Mattermost instance and knowledge of the bulk import feature.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 10.8.2, 10.7.4, 10.5.8, 9.11.17
Vendor Advisory: https://mattermost.com/security-updates
Restart Required: Yes
Instructions:
1. Backup your Mattermost instance. 2. Download the patched version from Mattermost releases. 3. Stop Mattermost service. 4. Replace with patched version. 5. Restart Mattermost service. 6. Verify version is updated.
🔧 Temporary Workarounds
Disable bulk import feature
allTemporarily disable the bulk import functionality to prevent exploitation.
Edit config.json: set 'EnableBulkImport' to false
Restart Mattermost service
Restrict admin access
allLimit system administrator accounts to trusted personnel only.
Review and audit admin user accounts
Implement MFA for admin accounts
🧯 If You Can't Patch
- Implement strict monitoring of bulk import activities and file access logs.
- Apply network segmentation to isolate Mattermost server from sensitive systems.
🔍 How to Verify
Check if Vulnerable:
Check Mattermost version via web interface Admin Console > System Console > About or run: grep 'Version' mattermost/config/config.jsonCheck Version:
grep 'Version' mattermost/config/config.jsonVerify Fix Applied:
Verify version is updated to patched version and test bulk import with path traversal attempts.📡 Detection & Monitoring
Log Indicators:
- Unusual bulk import activities
- File access attempts with path traversal patterns (e.g., '../../')
- Admin user accessing unexpected files
Network Indicators:
- Large bulk import file uploads from admin accounts
SIEM Query:
source='mattermost.log' AND ('bulk import' OR 'path traversal' OR '../../')