CVE-2021-43182
📋 TL;DR
This vulnerability in JetBrains Hub allows attackers to cause a Denial of Service (DoS) condition by manipulating user information. It affects all organizations running vulnerable versions of JetBrains Hub, potentially disrupting authentication and user management services.
💻 Affected Systems
- JetBrains Hub
📦 What is this software?
Hub by Jetbrains
⚠️ Risk & Real-World Impact
Worst Case
Complete service unavailability of JetBrains Hub, preventing user authentication, access to projects, and team collaboration features across the entire organization.
Likely Case
Temporary service degradation or intermittent outages affecting user login and management functions until the attack stops or the system recovers.
If Mitigated
Minimal impact with proper rate limiting, input validation, and monitoring in place to detect and block malicious requests before they cause service disruption.
🎯 Exploit Status
The vulnerability involves manipulating user information, which typically requires some level of access. The exact exploitation method is not publicly documented.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 2021.1.13415 and later
Vendor Advisory: https://blog.jetbrains.com/blog/2021/11/08/jetbrains-security-bulletin-q3-2021/
Restart Required: Yes
Instructions:
1. Backup your Hub data and configuration. 2. Download the patched version (2021.1.13415 or later) from the JetBrains website. 3. Stop the Hub service. 4. Install the updated version following JetBrains upgrade documentation. 5. Restart the Hub service. 6. Verify the service is running correctly.
🔧 Temporary Workarounds
Implement Rate Limiting
allConfigure rate limiting on user information endpoints to prevent abuse that could lead to DoS conditions.
# Configure in Hub application settings or via reverse proxy (nginx example):
limit_req_zone $binary_remote_addr zone=hubuser:10m rate=10r/s;
location /hub/api/rest/users {
limit_req zone=hubuser burst=20 nodelay;
}
Restrict Network Access
linuxLimit access to JetBrains Hub to trusted networks only, reducing the attack surface.
# Firewall rule example (iptables):
iptables -A INPUT -p tcp --dport 8080 -s 10.0.0.0/8 -j ACCEPT
iptables -A INPUT -p tcp --dport 8080 -j DROP
🧯 If You Can't Patch
- Implement strict network segmentation and firewall rules to limit access to JetBrains Hub only to necessary users and systems.
- Deploy a Web Application Firewall (WAF) with DoS protection rules and monitor for unusual patterns in user information requests.
🔍 How to Verify
Check if Vulnerable:
Check the Hub version in the administration interface or via the API endpoint /hub/api/rest/about. If version is below 2021.1.13415, the system is vulnerable.Check Version:
curl -s http://your-hub-server:port/hub/api/rest/about | grep -o '"version":"[^"]*"'Verify Fix Applied:
After patching, verify the version shows 2021.1.13415 or higher in the administration interface. Test user information functionality to ensure normal operation.📡 Detection & Monitoring
Log Indicators:
- Unusually high frequency of requests to user information endpoints
- Errors related to user data processing or memory exhaustion
- Multiple failed authentication attempts followed by user information requests
Network Indicators:
- Spike in traffic to /hub/api/rest/users endpoints
- Abnormal request patterns from single IP addresses
- Increased error rates (5xx responses) from Hub service
SIEM Query:
source="hub.log" AND ("POST /hub/api/rest/users" OR "GET /hub/api/rest/users") | stats count by src_ip | where count > 100