CVE-2025-13767
📋 TL;DR
This vulnerability allows authenticated Mattermost users with Jira plugin access to read posts and attachments from channels they shouldn't have access to. It affects Mattermost instances with the Jira integration enabled where users can attach posts to Jira issues. The issue occurs when the system fails to validate proper channel membership during this attachment process.
💻 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
An authenticated attacker could systematically exfiltrate sensitive information from private channels, including confidential discussions, file attachments, and proprietary data, leading to data breaches and compliance violations.
Likely Case
Users with legitimate access to the Jira plugin accidentally or intentionally viewing content from channels they shouldn't access, potentially exposing internal communications or sensitive project information.
If Mitigated
With proper access controls and monitoring, impact is limited to isolated incidents that can be quickly detected and contained through audit logs.
🎯 Exploit Status
Exploitation is straightforward for users with legitimate access to the Jira plugin functionality.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Update to Mattermost 11.1.1, 11.0.6, 10.12.4, or 10.11.8
Vendor Advisory: https://mattermost.com/security-updates
Restart Required: Yes
Instructions:
1. Backup your Mattermost instance and database. 2. Download the patched version from Mattermost downloads page. 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 Jira Integration
allTemporarily disable the Jira plugin to prevent exploitation while planning for patching.
mmctl plugin disable jira
Restrict Jira Plugin Access
allLimit which users have access to the Jira plugin functionality to reduce attack surface.
mmctl plugin enable jira --channel-team-only
🧯 If You Can't Patch
- Implement strict access controls and audit logging for Jira plugin usage
- Monitor for unusual patterns of post attachments to Jira issues from users
🔍 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 11.1.1, 11.0.6, 10.12.4, or 10.11.8 or higher📡 Detection & Monitoring
Log Indicators:
- Unusual patterns of post attachments to Jira issues
- Users accessing posts from channels they aren't members of
Network Indicators:
- Increased API calls to Jira integration endpoints
SIEM Query:
source="mattermost" AND (event="post_attached_to_jira" OR event="jira_plugin_used") | stats count by user, channel