CVE-2026-40190

Summary

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.

Affected Software

VendorProductVersion RangeStatus
langchain-ailangsmith-sdk< 0.5.18affected

Weaknesses

  • CWE-1321: CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')

ADP Enrichment

CISA ADP Vulnrichment

  • SSVC:
  • Exploitation: poc
    • Automatable: no
    • Technical Impact: partial

References