CVE-2024-36492
📋 TL;DR
This vulnerability in Mattermost allows a malicious remote user in a shared channel to overwrite an existing local user's account. This affects Mattermost servers running vulnerable versions with shared channels enabled. Attackers could potentially take over legitimate user accounts.
💻 Affected Systems
- Mattermost Team Edition
- Mattermost Enterprise Edition
📦 What is this software?
Mattermost by Mattermost
Mattermost by Mattermost
Mattermost by Mattermost
Mattermost by Mattermost
⚠️ Risk & Real-World Impact
Worst Case
Complete account takeover of any local user, allowing unauthorized access to sensitive communications, data exfiltration, and privilege escalation within the Mattermost instance.
Likely Case
Targeted account compromise of specific users in shared channels, leading to unauthorized access to team communications and potential lateral movement within the organization.
If Mitigated
Limited impact with proper access controls, monitoring, and network segmentation, though account integrity could still be compromised.
🎯 Exploit Status
Exploitation requires access to a shared channel as a remote user. The vulnerability is in the user synchronization mechanism between shared channels.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 9.9.1, 9.5.7, 9.7.6, 9.8.2
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.com/download. 3. Stop the Mattermost service. 4. Replace the binary/files with the patched version. 5. Restart the Mattermost service. 6. Verify the version is updated.
🔧 Temporary Workarounds
Disable Shared Channels
allTemporarily disable the shared channels feature to prevent exploitation while patching.
mmctl config set ExperimentalSettings.EnableSharedChannels false
Restrict Shared Channel Access
allLimit which organizations/users can create or join shared channels to reduce attack surface.
mmctl config set ExperimentalSettings.RestrictPrivateChannelManagement true
🧯 If You Can't Patch
- Disable shared channels feature entirely via configuration
- Implement strict network segmentation to isolate Mattermost from untrusted networks
🔍 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 9.9.1, 9.5.7, 9.7.6, or 9.8.2 or higher. Test user modification in shared channels is properly restricted.📡 Detection & Monitoring
Log Indicators:
- Unexpected user profile modifications
- Failed authentication attempts followed by successful login from same IP
- User synchronization errors in shared channels
Network Indicators:
- Unusual API calls to user modification endpoints from shared channel sources
SIEM Query:
source="mattermost" AND (event="user_updated" OR event="user_login") | stats count by user, source_ip