CVE-2023-39631
📋 TL;DR
This vulnerability allows remote attackers to execute arbitrary code through the evaluate function in LangChain's numexpr library integration. It affects LangChain installations using vulnerable versions, potentially compromising AI/ML applications built with this framework. Attackers can achieve remote code execution without authentication.
💻 Affected Systems
- LangChain-ai Langchain
📦 What is this software?
Langchain by Langchain
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise with attacker gaining full control over the server, allowing data theft, lateral movement, and persistent backdoor installation.
Likely Case
Remote code execution leading to application compromise, data exfiltration, and potential privilege escalation on the host system.
If Mitigated
Limited impact if proper input validation and sandboxing are implemented, though code execution may still be possible in some contexts.
🎯 Exploit Status
Exploitation requires sending malicious input to the evaluate function. The vulnerability is well-documented in public repositories with proof-of-concept examples available.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: v0.0.246 and later
Vendor Advisory: https://github.com/langchain-ai/langchain/issues/8363
Restart Required: Yes
Instructions:
1. Update LangChain to version 0.0.246 or later using pip: pip install --upgrade langchain==0.0.246
2. Restart all services using LangChain
3. Verify the update was successful
🔧 Temporary Workarounds
Disable numexpr evaluation
allDisable the vulnerable numexpr evaluation feature in LangChain configuration
Set environment variable: export LANGCHAIN_DISABLE_NUMEXPR=true
Or modify code: os.environ['LANGCHAIN_DISABLE_NUMEXPR'] = 'true'
Input validation and sanitization
allImplement strict input validation for all user inputs passed to evaluation functions
🧯 If You Can't Patch
- Implement network segmentation to isolate LangChain services from critical systems
- Deploy application-level firewalls with strict input validation rules for evaluation endpoints
🔍 How to Verify
Check if Vulnerable:
Check LangChain version and verify if numexpr evaluation is enabled in your applicationCheck Version:
python -c "import langchain; print(langchain.__version__)"Verify Fix Applied:
Verify LangChain version is 0.0.246 or later and test that malicious input to evaluate functions is properly rejected📡 Detection & Monitoring
Log Indicators:
- Unusual evaluation function calls
- Suspicious input patterns in expression evaluation logs
- Error messages related to numexpr evaluation failures
Network Indicators:
- Unusual outbound connections from LangChain services
- Traffic patterns indicating code execution attempts
SIEM Query:
source="langchain" AND (event="evaluate" OR event="numexpr") AND (input="*__import__*" OR input="*os.system*" OR input="*subprocess*" OR input="*eval*")