CVE-2025-47871
📋 TL;DR
This vulnerability allows authenticated Mattermost users who are members of a playbook but not members of a linked private channel to access sensitive information about that channel through the run metadata API endpoint. Affected users are those running vulnerable Mattermost versions with playbooks and private channels configured.
💻 Affected Systems
- Mattermost
📦 What is this software?
Mattermost Server by Mattermost
Mattermost Server by Mattermost
Mattermost Server by Mattermost
Mattermost Server by Mattermost
Mattermost Server by Mattermost
Mattermost Server by Mattermost
Mattermost Server by Mattermost
Mattermost Server by Mattermost
⚠️ Risk & Real-World Impact
Worst Case
Unauthorized disclosure of private channel names, display names, and participant counts could enable targeted social engineering, reconnaissance for further attacks, or exposure of confidential team structures.
Likely Case
Internal users accidentally or intentionally accessing metadata about private channels they shouldn't see, potentially violating data privacy policies or exposing organizational structures.
If Mitigated
Limited exposure of non-critical metadata with no access to actual channel content or messages.
🎯 Exploit Status
Exploitation requires valid user credentials and access to a playbook that links to private channels.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Mattermost 10.5.6, 9.11.16, 10.8.1, 10.7.3, 10.6.6 or later
Vendor Advisory: https://mattermost.com/security-updates
Restart Required: Yes
Instructions:
1. Backup your Mattermost installation and database. 2. Download the patched version from mattermost.com/download. 3. Stop the Mattermost service. 4. Replace the installation with the patched version. 5. Restart the Mattermost service. 6. Verify the version is updated.
🔧 Temporary Workarounds
Disable Playbooks Plugin
allTemporarily disable the Playbooks plugin to prevent exploitation while planning upgrade.
mmctl plugin disable playbooks
Restrict API Access
allUse network controls or WAF to restrict access to the playbook run metadata API endpoint.
🧯 If You Can't Patch
- Implement strict access controls and monitor for unusual API calls to playbook endpoints.
- Audit user permissions and ensure least privilege access to playbooks and channels.
🔍 How to Verify
Check if Vulnerable:
Check Mattermost version via System Console > About or run: mmctl versionCheck Version:
mmctl versionVerify Fix Applied:
Verify version is patched (10.5.6+, 9.11.16+, 10.8.1+, 10.7.3+, or 10.6.6+) and test that non-channel members cannot retrieve private channel metadata via playbook run API.📡 Detection & Monitoring
Log Indicators:
- Unusual API calls to /plugins/playbooks/api/v0/runs/{id}/metadata from users not in corresponding private channels
- Multiple failed permission checks for channel membership
Network Indicators:
- HTTP GET requests to playbook run metadata endpoints returning 200 OK for users without channel access
SIEM Query:
source="mattermost" AND (uri_path="/plugins/playbooks/api/v0/runs/*/metadata" OR message="channel membership check")