CVE-2023-39659 is a critical-severity (CVSS 9.8) CWE-74 vulnerability in langchain. 1 public exploit or proof-of-concept reference is indexed, so weaponization risk is real. A fix is available for langchain — see the affected versions and patch details below.
LangChain vulnerable to arbitrary code execution
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- A successful exploit gives an attacker total control of the affected component, not partial access.
Exploitation and automatability from CISA’s SSVC triage for CVE-2023-39659.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
langchainReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.
Description
An issue in langchain langchain-ai v.0.0.232 and before allows a remote attacker to execute arbitrary code via a crafted script to the PythonAstREPLTool._run component.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | langchain | all versions | 0.0.325pip install --upgrade 'langchain==0.0.325' |
Affected Products
langchainlangchainResearch use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for langchain, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update langchain to 0.0.325 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2023-39659 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
Frequently Asked Questions
Is CVE-2023-39659 in your dependencies?
Find it across PyPI, including transitive dependencies.