CVE-2024-11599
📋 TL;DR
This vulnerability allows unauthenticated attackers to bypass email domain restrictions in Mattermost by submitting specially crafted email addresses during registration. Affected organizations are those running vulnerable Mattermost versions with email domain restrictions configured.
💻 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
Unauthorized users from prohibited domains gain access to the Mattermost instance, potentially leading to data exposure, privilege escalation, or further attacks within the organization's collaboration platform.
Likely Case
Attackers bypass email domain restrictions to create accounts, enabling them to access internal communications and potentially phish legitimate users.
If Mitigated
With proper monitoring and access controls, impact is limited to unauthorized account creation which can be detected and remediated.
🎯 Exploit Status
Exploitation requires knowledge of email validation bypass techniques but no authentication is needed.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 10.0.2, 10.1.2, 9.11.4, 9.5.12
Vendor Advisory: https://mattermost.com/security-updates
Restart Required: Yes
Instructions:
1. Backup Mattermost data and configuration. 2. Download patched version from Mattermost downloads page. 3. Stop Mattermost service. 4. Install patched version. 5. Restart Mattermost service. 6. Verify version and functionality.
🔧 Temporary Workarounds
Disable Email Registration
allTemporarily disable email-based user registration to prevent exploitation
Edit config.json: set 'EnableSignUpWithEmail' to false
Restart Mattermost service
Enable Additional Authentication
allRequire additional authentication methods like SSO or LDAP
Configure SSO/LDAP in Mattermost System Console
Disable local email authentication
🧯 If You Can't Patch
- Implement network-level restrictions to limit registration attempts
- Enable detailed logging of registration attempts and monitor for suspicious patterns
🔍 How to Verify
Check if Vulnerable:
Check Mattermost version via System Console > About Mattermost or run: mattermost versionCheck Version:
mattermost versionVerify Fix Applied:
Verify version is patched (10.0.2, 10.1.2, 9.11.4, or 9.5.12) and test email registration with malformed addresses📡 Detection & Monitoring
Log Indicators:
- Unusual registration attempts with non-standard email formats
- Successful registrations from previously restricted domains
Network Indicators:
- Spike in registration requests
- Registration attempts with malformed email addresses
SIEM Query:
source="mattermost" AND (event="user_created" OR event="user_registered") AND email="*@*"