CVE-2023-6458
📋 TL;DR
Mattermost web applications fail to properly validate route parameters in the team/channel URL path, allowing attackers to perform client-side path traversal. This vulnerability affects Mattermost instances with web interfaces, potentially exposing unauthorized data or functionality to authenticated users.
💻 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
Attackers could access unauthorized channels, sensitive data, or perform actions in other teams/channels they shouldn't have access to, leading to data leakage or privilege escalation.
Likely Case
Authenticated users could access channels or teams they're not authorized to view, violating access controls and potentially exposing sensitive conversations or files.
If Mitigated
With proper network segmentation and access controls, impact is limited to the Mattermost application scope only.
🎯 Exploit Status
Exploitation requires authenticated access but is technically simple once authenticated
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Check Mattermost security updates for specific patched version
Vendor Advisory: https://mattermost.com/security-updates
Restart Required: Yes
Instructions:
1. Check Mattermost security updates page for patch details. 2. Upgrade to patched version. 3. Restart Mattermost service. 4. Verify fix by testing URL parameter validation.
🔧 Temporary Workarounds
Web Application Firewall Rule
allImplement WAF rules to block suspicious URL patterns containing path traversal attempts
Access Restriction
allRestrict Mattermost access to trusted networks only
🧯 If You Can't Patch
- Implement strict network segmentation to isolate Mattermost from sensitive systems
- Enforce principle of least privilege for all Mattermost user accounts
🔍 How to Verify
Check if Vulnerable:
Test if URL parameters can be manipulated to access unauthorized channels/teams while authenticatedCheck Version:
Check Mattermost admin panel or run appropriate version command for your installation methodVerify Fix Applied:
After patching, attempt same path traversal tests and confirm they are blocked📡 Detection & Monitoring
Log Indicators:
- Unusual access patterns to channels
- Failed authorization attempts with manipulated URLs
- Access to channels by users not in those teams
Network Indicators:
- HTTP requests with unusual URL parameters
- Patterns of access to sequential channel IDs
SIEM Query:
Search for HTTP requests containing '/channels/' with unusual parameter values or access patterns