CVE-2026-40190

MEDIUM

5.6

Description

LangSmith Client SDKs provide SDK's for interacting with the LangSmith platform. Prior to 0.5.18, the LangSmith JavaScript/TypeScript SDK (langsmith) contains an incomplete prototype pollution fix in its internally vendored lodash set() utility. The baseAssignValue() function only guards against the __proto__ key, but fails to prevent traversal via constructor.prototype. This allows an attacker who controls keys in data processed by the createAnonymizer() API to pollute Object.prototype, affecting all objects in the Node.js process. This vulnerability is fixed in 0.5.18.

CVE Details

CVSS v3.1 Score5.6

SeverityMEDIUM

CVSS VectorCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L

Attack VectorNETWORK

ComplexityHIGH

Privileges RequiredNONE

User InteractionNONE

Published4/10/2026

Last Modified4/13/2026

Sourcenvd

Honeypot Sightings0

Weaknesses (CWE)

CWE-1321

References

https://github.com/langchain-ai/langsmith-sdk/security/advisories/GHSA-fw9q-39r9-c252(security-advisories@github.com)

IOC Correlations

No correlations recorded

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