CVE-2025-56869
📋 TL;DR
This directory traversal vulnerability in Sync In server allows authenticated attackers to read and write arbitrary files on the system by exploiting insufficient path validation in the FilesManager service. It affects all Sync In server installations up to version 1.1.1. Attackers need valid credentials to exploit this vulnerability.
💻 Affected Systems
- Sync In server
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise through arbitrary file write leading to remote code execution, or sensitive data exfiltration through arbitrary file read.
Likely Case
Unauthorized access to sensitive configuration files, user data, or ability to modify application files to maintain persistence.
If Mitigated
Limited impact if proper file system permissions restrict the application's access and network segmentation limits attacker movement.
🎯 Exploit Status
Exploitation requires understanding of the API endpoints and authentication. The specific vulnerable functions are identified in the CVE description.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: v1.2.0
Vendor Advisory: https://github.com/Sync-in/server/releases/tag/v1.2.0
Restart Required: No
Instructions:
1. Download v1.2.0 from the GitHub releases page. 2. Stop the Sync In server service. 3. Replace the existing installation with the new version. 4. Restart the Sync In server service.
🔧 Temporary Workarounds
Restrict file system permissions
allLimit the Sync In server process to only necessary directories using file system permissions or containerization.
Implement WAF rules
allAdd web application firewall rules to block directory traversal patterns in file upload requests.
🧯 If You Can't Patch
- Implement strict network segmentation to isolate the Sync In server from sensitive systems.
- Enforce strong authentication policies and monitor for suspicious file access patterns.
🔍 How to Verify
Check if Vulnerable:
Check the Sync In server version. If it's 1.1.1 or earlier, it's vulnerable.Check Version:
Check the server version in the web interface or configuration files, or run: npm list sync-in-server if installed via npm.Verify Fix Applied:
Verify the version is 1.2.0 or later and test file upload functionality with traversal attempts.📡 Detection & Monitoring
Log Indicators:
- Unusual file access patterns outside expected directories
- Multiple failed authentication attempts followed by file operations
- File upload requests containing '../' sequences
Network Indicators:
- HTTP requests to file upload endpoints with path traversal sequences in parameters
SIEM Query:
source="sync-in-logs" AND (message="*../*" OR message="*..\\*" OR message="*%2e%2e%2f*")