CVE-2023-39631 is a critical-severity (CVSS 9.8) Code Injection vulnerability in langchain. 2 public exploit or proof-of-concept references are 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 via the evaluate function in the numexpr library
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-2023-39631.
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
langchain🐍numexprReal-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 LanChain-ai Langchain v.0.0.245 allows a remote attacker to execute arbitrary code via the evaluate function in the numexpr library.
Patches: Released in v.0.0.308. numexpr dependency is optional for langchain.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | langchain | all versions | 0.0.308pip install --upgrade 'langchain==0.0.308' |
| 🐍PyPI | numexpr | all versions | 2.8.5pip install --upgrade 'numexpr==2.8.5' |
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 0.0.308 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2023-39631 is resolved across your whole dependency graph.
Workarounds
Stop passing untrusted input into the interpreter or shell: call the affected binary with an argument array rather than a composed command string, reject anything outside a strict allowlist of expected values, and run the component under an account that cannot reach beyond the work it legitimately does.
Frequently Asked Questions
Is CVE-2023-39631 in your dependencies?
Find it across PyPI, including transitive dependencies.