CVE-2025-58075
📋 TL;DR
This vulnerability allows attackers to join any Mattermost team without proper authorization by manipulating RelayState parameters. Attackers can bypass team invitation restrictions and gain unauthorized access to teams. All Mattermost servers running affected versions are vulnerable.
💻 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
Complete compromise of team privacy and data confidentiality as attackers join any team, access sensitive communications, and potentially escalate privileges within the platform.
Likely Case
Unauthorized access to internal teams, exposure of sensitive business communications, and potential data leakage from private channels.
If Mitigated
Limited impact if teams contain only public information or if additional access controls monitor and restrict new member activities.
🎯 Exploit Status
Exploitation requires some user interaction but is technically simple once the vulnerability is understood.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 10.11.2, 10.10.3, 10.5.11 or later
Vendor Advisory: https://mattermost.com/security-updates
Restart Required: Yes
Instructions:
1. Backup your Mattermost database and configuration. 2. Download the patched version from Mattermost downloads. 3. Stop Mattermost service. 4. Install the patched version. 5. Restart Mattermost service. 6. Verify the version is updated.
🔧 Temporary Workarounds
Disable team invitations
allTemporarily disable all team invitation functionality to prevent exploitation
Update config.json: "EnableTeamCreation": false, "RestrictTeamInvite": "all"
🧯 If You Can't Patch
- Implement network segmentation to restrict Mattermost access to trusted users only
- Enable detailed audit logging and monitor for unauthorized team join attempts
🔍 How to Verify
Check if Vulnerable:
Check Mattermost version via System Console > About or run: mattermost versionCheck Version:
mattermost versionVerify Fix Applied:
Verify version is 10.11.2+, 10.10.3+, or 10.5.11+ and test team invitation functionality📡 Detection & Monitoring
Log Indicators:
- Unexpected team join events
- Team membership changes from unusual IPs
- Multiple failed invitation attempts followed by successful join
Network Indicators:
- Unusual patterns of POST requests to team invitation endpoints
- Traffic containing manipulated RelayState parameters
SIEM Query:
source="mattermost" AND (event="team_join" OR event="user_added") | stats count by src_ip, user