CVE-2021-31863
📋 TL;DR
This vulnerability allows authenticated Redmine users to read arbitrary local files accessible by the application server process due to insufficient input validation in Git repository integration. It affects Redmine installations before version 4.0.9, 4.1.x before 4.1.3, and 4.2.x before 4.2.1. Attackers can exploit this to access sensitive files like configuration files, credentials, or other data stored on the server.
💻 Affected Systems
- Redmine
📦 What is this software?
Redmine by Redmine
Redmine by Redmine
Redmine by Redmine
⚠️ Risk & Real-World Impact
Worst Case
Attackers gain access to sensitive system files, configuration files containing credentials, SSH keys, database passwords, or other proprietary data, potentially leading to full system compromise.
Likely Case
Authenticated users read configuration files, source code, or other sensitive files stored on the server, leading to information disclosure and potential credential theft.
If Mitigated
Limited to reading files accessible by the Redmine application server user, with proper file permissions preventing access to critical system files.
🎯 Exploit Status
Exploitation requires authenticated user access. Public proof-of-concept code exists demonstrating file reading.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Redmine 4.0.9, 4.1.3, 4.2.1 or later
Vendor Advisory: https://www.redmine.org/projects/redmine/wiki/Security_Advisories
Restart Required: Yes
Instructions:
1. Backup your Redmine installation and database. 2. Download the patched version from redmine.org. 3. Follow the Redmine upgrade instructions for your version. 4. Restart the application server.
🔧 Temporary Workarounds
Disable Git Repository Integration
allTemporarily disable the vulnerable Git repository integration feature
Edit Redmine configuration to disable repository features or remove repository settings
Restrict File Permissions
linuxLimit file system permissions for the Redmine application server user
chmod 600 /path/to/sensitive/files
chown root:root /path/to/sensitive/files
🧯 If You Can't Patch
- Implement strict network segmentation to isolate Redmine servers
- Apply additional authentication controls and monitor for suspicious file access patterns
🔍 How to Verify
Check if Vulnerable:
Check Redmine version via admin interface or by examining the application filesCheck Version:
Check Redmine version in Admin → Information or examine VERSION file in installation directoryVerify Fix Applied:
Verify Redmine version is 4.0.9, 4.1.3, 4.2.1 or later and test Git repository functionality📡 Detection & Monitoring
Log Indicators:
- Unusual file access patterns in application logs
- Multiple failed or unusual Git repository operations
Network Indicators:
- Unusual outbound connections from Redmine server
SIEM Query:
source="redmine.log" AND ("repository" OR "git") AND ("error" OR "access" OR "permission")🔗 References
- https://lists.debian.org/debian-lts-announce/2021/05/msg00013.html
- https://www.redmine.org/news/131
- https://www.redmine.org/projects/redmine/wiki/Security_Advisories
- https://lists.debian.org/debian-lts-announce/2021/05/msg00013.html
- https://www.redmine.org/news/131
- https://www.redmine.org/projects/redmine/wiki/Security_Advisories
