CVE-2025-53910
📋 TL;DR
The Mattermost Confluence Plugin vulnerability allows attackers to create unauthorized channel subscriptions via API calls. This affects organizations using Mattermost with the Confluence plugin before version 1.5.0, potentially enabling unauthorized access to channel notifications.
💻 Affected Systems
- Mattermost Confluence Plugin
📦 What is this software?
Confluence by Mattermost
⚠️ Risk & Real-World Impact
Worst Case
Attackers could subscribe to sensitive channels, gaining access to confidential notifications and potentially using this as a foothold for further attacks.
Likely Case
Unauthorized users subscribe to channels they shouldn't access, receiving notifications about sensitive discussions or data.
If Mitigated
Minimal impact with proper access controls and monitoring in place.
🎯 Exploit Status
Requires authenticated API access to the edit channel subscription endpoint.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 1.5.0
Vendor Advisory: https://mattermost.com/security-updates
Restart Required: No
Instructions:
1. Access Mattermost System Console. 2. Navigate to Plugin Management. 3. Update Confluence Plugin to version 1.5.0 or higher. 4. Verify plugin is active and functioning.
🔧 Temporary Workarounds
Disable Confluence Plugin
allTemporarily disable the vulnerable plugin until patching is possible.
mmctl plugin disable com.mattermost.confluence
Restrict API Access
allImplement network controls to restrict access to Mattermost API endpoints.
🧯 If You Can't Patch
- Implement strict access controls and monitor for unusual subscription activity.
- Disable the Confluence plugin entirely until patching is possible.
🔍 How to Verify
Check if Vulnerable:
Check Confluence plugin version in Mattermost System Console > Plugin Management.Check Version:
mmctl plugin list | grep confluenceVerify Fix Applied:
Confirm plugin version is 1.5.0 or higher and test channel subscription permissions.📡 Detection & Monitoring
Log Indicators:
- Unusual channel subscription creation events
- API calls to edit channel subscription endpoint from unauthorized users
Network Indicators:
- POST requests to /plugins/com.mattermost.confluence/api/v1/subscriptions endpoint
SIEM Query:
source="mattermost" AND (event="channel_subscription_created" OR path="/plugins/com.mattermost.confluence/api/v1/subscriptions")