CVE-2025-25274
📋 TL;DR
This vulnerability allows authenticated users to execute slash commands in archived Mattermost channels, bypassing intended restrictions. It affects Mattermost instances running vulnerable versions, requiring user authentication but no special privileges.
💻 Affected Systems
- Mattermost
📦 What is this software?
Mattermost Server by Mattermost
Mattermost Server by Mattermost
Mattermost Server by Mattermost
⚠️ Risk & Real-World Impact
Worst Case
Authenticated users could execute unauthorized commands in archived channels, potentially accessing sensitive information or performing actions that should be restricted to active channels.
Likely Case
Users with access to archived channels could run commands that bypass normal channel state restrictions, potentially causing confusion or minor disruption.
If Mitigated
With proper access controls and monitoring, impact is limited to authorized users performing actions in channels they already have access to.
🎯 Exploit Status
Exploitation requires authenticated access to archived channels
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Update to Mattermost 10.4.3, 10.3.4, or 9.11.9
Vendor Advisory: https://mattermost.com/security-updates
Restart Required: Yes
Instructions:
1. Backup your Mattermost instance. 2. Download the patched version from Mattermost downloads. 3. Stop Mattermost service. 4. Install the update. 5. Restart Mattermost service. 6. Verify version update.
🔧 Temporary Workarounds
Disable slash commands globally
allTemporarily disable all slash commands to prevent exploitation
Edit config.json: set "EnableCommands" to false
Restrict archived channel access
allLimit user permissions for archived channels
Use Mattermost System Console to adjust channel permissions
🧯 If You Can't Patch
- Review and restrict user permissions for archived channels
- Monitor logs for unusual command execution in archived channels
🔍 How to Verify
Check if Vulnerable:
Check Mattermost version via System Console > About MattermostCheck Version:
mattermost versionVerify Fix Applied:
Verify version is 10.4.3, 10.3.4, 9.11.9 or later📡 Detection & Monitoring
Log Indicators:
- Slash command execution in archived channels
- Unexpected command usage patterns
Network Indicators:
- API calls to archived channel endpoints with command parameters
SIEM Query:
source="mattermost" AND ("archived" AND "command")