CVE-2021-31905
📋 TL;DR
This vulnerability in JetBrains YouTrack allows unauthorized information disclosure through issue previews. Attackers can potentially access sensitive data that should be restricted. Organizations using YouTrack versions before 2020.6.8801 are affected.
💻 Affected Systems
- JetBrains YouTrack
📦 What is this software?
Youtrack by Jetbrains
⚠️ Risk & Real-World Impact
Worst Case
Complete exposure of confidential issue data including attachments, comments, and metadata to unauthorized users
Likely Case
Limited information leakage of issue details to users with partial access permissions
If Mitigated
No data exposure with proper access controls and updated software
🎯 Exploit Status
Information disclosure vulnerabilities typically require some level of access but are easy to exploit once discovered
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 2020.6.8801 and later
Vendor Advisory: https://blog.jetbrains.com/blog/2021/05/07/jetbrains-security-bulletin-q1-2021/
Restart Required: Yes
Instructions:
1. Backup your YouTrack instance. 2. Download YouTrack 2020.6.8801 or later from JetBrains. 3. Stop the YouTrack service. 4. Install the updated version. 5. Restart the YouTrack service. 6. Verify the update was successful.
🔧 Temporary Workarounds
Restrict Issue Preview Access
allTemporarily disable or restrict issue preview functionality for all users
Enforce Strict Access Controls
allImplement additional permission checks and audit all user access to sensitive issues
🧯 If You Can't Patch
- Implement network segmentation to isolate YouTrack from untrusted networks
- Enable detailed logging and monitoring for unusual access patterns to issue previews
🔍 How to Verify
Check if Vulnerable:
Check YouTrack version in Administration → Server Settings → Version InformationCheck Version:
Check web interface at /admin/serverSettings or use YouTrack REST APIVerify Fix Applied:
Confirm version is 2020.6.8801 or later and test issue preview functionality with different user permissions📡 Detection & Monitoring
Log Indicators:
- Unusual access patterns to issue previews
- Multiple failed permission checks for issue access
- Access to issues by users without proper permissions
Network Indicators:
- Increased traffic to issue preview endpoints
- Requests for issue data from unexpected sources
SIEM Query:
source="youtrack" AND (event="issue_preview" OR event="permission_denied") AND user NOT IN authorized_users