CVE-2025-14435
📋 TL;DR
This vulnerability allows authenticated Mattermost users to trigger infinite component re-render loops when API errors occur, causing application-level denial of service. Affected systems include Mattermost versions 10.11.x up to 10.11.8, 11.1.x up to 11.1.1, and 11.0.x up to 11.0.6.
💻 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 application unavailability affecting all users, requiring service restart and potential data loss during downtime.
Likely Case
Degraded performance or temporary service disruption for some users until the malicious session is terminated.
If Mitigated
Minimal impact with proper monitoring and quick response to anomalous behavior patterns.
🎯 Exploit Status
Exploitation requires authenticated access but is technically simple once access is obtained.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 10.11.9, 11.1.2, 11.0.7 or later
Vendor Advisory: https://mattermost.com/security-updates
Restart Required: Yes
Instructions:
1. Backup Mattermost data and configuration. 2. Stop Mattermost service. 3. Update to patched version using your deployment method (package manager, Docker, etc.). 4. Restart Mattermost service. 5. Verify functionality.
🔧 Temporary Workarounds
Rate Limiting Enhancement
allImplement stricter API rate limiting to reduce impact of re-render loops
Configure rate limiting in Mattermost config.json: {"RateLimitSettings": {"Enable": true, "PerSec": 10, "MaxBurst": 100}}
Session Monitoring and Termination
linuxMonitor for abnormal session activity and terminate suspicious sessions
Use Mattermost CLI: mattermost user sessions list | grep -i suspicious
mattermost user sessions revoke [SESSION_ID]
🧯 If You Can't Patch
- Implement strict access controls and monitor for abnormal user behavior patterns
- Deploy web application firewall rules to detect and block excessive API error patterns
🔍 How to Verify
Check if Vulnerable:
Check Mattermost version via web interface (Main Menu > About Mattermost) or CLI: mattermost versionCheck Version:
mattermost versionVerify Fix Applied:
Confirm version is 10.11.9+, 11.1.2+, or 11.0.7+ and test API error handling📡 Detection & Monitoring
Log Indicators:
- Excessive 'API error' or 'component re-render' messages in Mattermost logs
- Unusual spike in CPU/memory usage correlated with specific user sessions
Network Indicators:
- Abnormally high number of API error responses to single user session
- Increased response times for all users
SIEM Query:
source="mattermost.log" AND ("API error" OR "re-render") | stats count by user_id | where count > 100