CVE-2021-31901
📋 TL;DR
This vulnerability in JetBrains Hub allows attackers to bypass two-factor authentication for users in the 'All Users' group. It affects organizations using JetBrains Hub for identity management and single sign-on. The flaw enables unauthorized access to protected systems and data.
💻 Affected Systems
- JetBrains Hub
📦 What is this software?
Hub by Jetbrains
⚠️ Risk & Real-World Impact
Worst Case
Attackers gain unauthorized access to all Hub-managed systems and sensitive user data, potentially leading to data breaches, privilege escalation, and lateral movement across the network.
Likely Case
Attackers bypass 2FA for targeted users, gaining unauthorized access to Hub-managed applications and potentially sensitive organizational resources.
If Mitigated
With proper network segmentation and monitoring, impact is limited to Hub system itself with minimal lateral movement potential.
🎯 Exploit Status
Exploitation requires access to Hub interface but authentication bypass is straightforward once access is obtained.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 2021.1.13079 or later
Vendor Advisory: https://blog.jetbrains.com/blog/2021/05/07/jetbrains-security-bulletin-q1-2021/
Restart Required: Yes
Instructions:
1. Backup Hub configuration and data. 2. Download and install Hub version 2021.1.13079 or later from JetBrains website. 3. Restart Hub service. 4. Verify 2FA is properly enforced for All Users group.
🔧 Temporary Workarounds
Disable All Users Group
allTemporarily disable or remove users from the 'All Users' group to prevent exploitation
Navigate to Hub Admin → Groups → All Users → Disable or remove members
Network Segmentation
allRestrict access to Hub administration interface to trusted IP addresses only
Configure firewall rules to limit Hub admin interface access
🧯 If You Can't Patch
- Implement strict network access controls to limit who can reach the Hub interface
- Enable enhanced logging and monitoring for authentication events and group membership changes
🔍 How to Verify
Check if Vulnerable:
Check Hub version in Admin interface. If version is below 2021.1.13079, system is vulnerable.Check Version:
Check Hub Admin dashboard or run: curl -k https://hub-server/admin/api/versionVerify Fix Applied:
After patching, verify version is 2021.1.13079 or later and test that 2FA is enforced for All Users group members.📡 Detection & Monitoring
Log Indicators:
- Failed 2FA attempts for All Users group members
- Unauthorized access to Hub admin interface
- Group membership changes without proper authentication
Network Indicators:
- Unusual authentication traffic patterns to Hub
- Access attempts from unexpected IP addresses
SIEM Query:
source="hub" AND (event_type="auth_failure" OR event_type="group_change") AND group="All Users"