What is CVE-2023-39659?

CVE-2023-39659 is a critical-severity vulnerability in Langchain, classified under Improper Neutralization of Special Elements in Output Used by a Downstream Component (Injection). CVSS score: 9.8/10. Published 2023-08-15.

How severe is CVE-2023-39659?

Critical severity. CVSS v3 base score is 9.8 out of 10.

Vulnerability in Langchain

CVE-2023-39659

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.

Published 2023-08-15 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.015 (73.8th percentile), scored 2026-09-29.

Low probability of exploitation in the next 30 days, but still tracked. 74th percentile — 73.8% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.015 · newest: 0.015 · change: 0.000

Affected products

Langchain

Weakness classification (CWE)

CWE-74 — Improper Neutralization of Special Elements in Output Used by a Downstream Component (Injection)

References

github.com/langchain-ai/langchain/issues/7700 (Exploit, Third Party Advisory, Issue Tracking)
github.com/langchain-ai/langchain/pull/5640 (Patch, Issue Tracking)

Frequently asked questions

What is CVE-2023-39659?: CVE-2023-39659 is a critical-severity vulnerability in Langchain, classified under Improper Neutralization of Special Elements in Output Used by a Downstream Component (Injection). CVSS score: 9.8/10. Published 2023-08-15.
How severe is CVE-2023-39659?: Critical severity. CVSS v3 base score is 9.8 out of 10.