CVE-2025-6854
📋 TL;DR
This path traversal vulnerability in Langchain-Chatchat allows attackers to access files outside the intended directory via the /v1/files endpoint. It affects all users running vulnerable versions of Langchain-Chatchat, particularly those with internet-facing deployments. The vulnerability can be exploited remotely without authentication.
💻 Affected Systems
- Langchain-Chatchat
📦 What is this software?
Langchain Chatchat by Chatchat Space
⚠️ Risk & Real-World Impact
Worst Case
Attackers could read sensitive system files, configuration files, or source code, potentially leading to credential theft, system compromise, or data exfiltration.
Likely Case
Unauthorized file reading of application files, configuration files, or adjacent user data within the application's directory structure.
If Mitigated
Limited impact with proper file permissions and network segmentation, potentially only allowing access to non-sensitive application files.
🎯 Exploit Status
Exploit details have been publicly disclosed in GitHub issue #5353. The vulnerability is straightforward to exploit with basic HTTP requests.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 0.3.2 or later
Vendor Advisory: https://github.com/chatchat-space/Langchain-Chatchat/issues/5353
Restart Required: Yes
Instructions:
1. Update Langchain-Chatchat to version 0.3.2 or later. 2. Restart the application service. 3. Verify the fix by testing the vulnerable endpoint.
🔧 Temporary Workarounds
Block Vulnerable Endpoint
allTemporarily block or disable the /v1/files endpoint until patching is complete
# Configure web server (nginx example)
location /v1/files { deny all; }
# Application firewall rule to block /v1/files
Input Validation
allImplement input validation to reject path traversal sequences
# Python example for path validation
import os
from pathlib import Path
def safe_path(user_input):
base_path = Path('/safe/directory')
requested = (base_path / user_input).resolve()
if not str(requested).startswith(str(base_path)):
raise ValueError('Path traversal attempt detected')
🧯 If You Can't Patch
- Implement strict network access controls to limit access to the vulnerable endpoint
- Deploy a web application firewall (WAF) with path traversal protection rules
🔍 How to Verify
Check if Vulnerable:
Test the endpoint with path traversal payloads like /v1/files?purpose=assistants&filename=../../../etc/passwd and check if it returns unauthorized filesCheck Version:
Check the application version in the interface or run: python -c "import langchain_chatchat; print(langchain_chatchat.__version__)"Verify Fix Applied:
After patching, retest with the same path traversal payloads - they should return errors or be blocked📡 Detection & Monitoring
Log Indicators:
- HTTP requests to /v1/files with ../ sequences in parameters
- Unusual file access patterns from the application
Network Indicators:
- Multiple requests to /v1/files with varying path traversal payloads
- Unusual outbound data transfers following file access
SIEM Query:
source="web_logs" AND uri_path="/v1/files" AND (param="*../*" OR param="*..\\*" OR param="*%2e%2e%2f*")