CVE-2023-34540 - Arbitrary Code Execution in LangChain ..171 – What You Need To Know
*Written exclusively for you: a simple explanation, code snippet, analysis, and links concerning the dangerous Langchain ..171 vulnerability.*
What Is LangChain?
LangChain is a Python library for building applications powered by large language models (LLMs). Developers use it for tasks like chatbots, document analysis, and agent frameworks.
About the Vulnerability: CVE-2023-34540
In June 2023, CVE-2023-34540 was assigned to a critical vulnerability in Langchain ..171. This bug lets a remote attacker run any Python code on the victim’s machine—with zero user interaction—if certain API endpoints are exposed, or if unsafe data is loaded.
Risk: If you use LangChain ..171 (or earlier), an attacker could take control of your server!
Where’s The Bug?
The problem exists in the load_tools and load_chain functionality. These functions can take untrusted input—plain text or JSON—and process it in a way that allows execution of arbitrary Python code.
langchain.chains.load_chain
The dangerous behavior comes from using eval() or loading YAML without safe loaders.
Demonstrating The Exploit
Below is a *simple code snippet* showing how an attacker can exploit the vulnerability.
> Suppose your API endpoint or app calls langchain.chains.load_chain on user-provided input. Here’s the kind of code you might accidentally write:
from langchain.chains import load_chain
# This simulates loading a chain definition provided by a user or file.
user_input = """
!!python/object/apply:os.system ["echo HACKED > /tmp/vulnerable"]
"""
# UNSAFE: This call can execute arbitrary OS commands!
chain = load_chain(user_input)
What happens?
When run, this will write “HACKED” into /tmp/vulnerable. That’s bad, because an attacker could run *anything* — like deleting files or installing malware.
Real-World Impact
If any part of your application
Loads chain config, tool config, or YAML from a remote user
- Uses automatic chain/tool loading from files or text
Upgrade LangChain:
Update to a version after ..171 (see changelog).
References
- CVE-2023-34540 NVD Entry
- Langchain Security Advisory (GitHub)
- Langchain Vulnerability Patch
- More details from oss-security
Summary
CVE-2023-34540 is dangerous. Langchain ..171 lets attackers run any code if you load untrusted chain/tool config. Don’t risk it—upgrade now, audit your code, and never deserialize untrusted data without strict checks.
Be safe and keep building!
*If you want more technical details or need help reviewing your app, let us know!*
Timeline
Published on: 06/14/2023 15:15:00 UTC
Last modified on: 06/23/2023 13:55:00 UTC