Vulnerability in Langchain Langchain_core
CVE-2026-40087
LangChain is a framework for building agents and LLM-powered applications. Prior to 0.3.84 and 1.2.28, LangChain's f-string prompt-template validation was incomplete in two respects. First, some prompt template classes accepted f-string te…
EPSS: 0.003 (17.8th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N.
Affected products
- Langchain Langchain_core
- Langchain-ai Langchain — versions < 0.3.83, >= 1.0.0a1, < 1.2.28
Weakness classification (CWE)
References
- security-advisories@github.com (x_refsource_CONFIRM, Mitigation, Vendor Advisory)
- security-advisories@github.com (Patch, x_refsource_MISC, Issue Tracking)
- security-advisories@github.com (Patch, x_refsource_MISC, Issue Tracking)
- security-advisories@github.com (Patch, x_refsource_MISC)
- security-advisories@github.com (Patch, x_refsource_MISC)
- security-advisories@github.com (Product, x_refsource_MISC, Release Notes)
- security-advisories@github.com (Product, x_refsource_MISC, Release Notes)
Frequently asked questions
- What is CVE-2026-40087?
- CVE-2026-40087 is a medium-severity vulnerability in Langchain Langchain_core, classified under Improper Neutralization of Special Elements Used in a Template Engine. CVSS score: 5.3/10. Published 2026-04-09.
- How severe is CVE-2026-40087?
- Medium severity. CVSS v3 base score is 5.3 out of 10.