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.
History

Mon, 13 Apr 2026 17:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Mon, 13 Apr 2026 13:00:00 +0000

Type Values Removed Values Added
First Time appeared Langchain-ai
Langchain-ai langsmith-sdk
Vendors & Products Langchain-ai
Langchain-ai langsmith-sdk

Fri, 10 Apr 2026 20:00:00 +0000

Type Values Removed Values Added
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.
Title LangSmith Client SDKs has Prototype Pollution in langsmith-sdk via Incomplete `__proto__` Guard in Internal lodash `set()`
Weaknesses CWE-1321
References
Metrics cvssV3_1

{'score': 5.6, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L'}


cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published: 2026-04-10T19:47:57.642Z

Updated: 2026-04-13T16:13:45.532Z

Reserved: 2026-04-09T20:59:17.620Z

Link: CVE-2026-40190

cve-icon Vulnrichment

Updated: 2026-04-13T16:13:41.123Z

cve-icon NVD

Status : Awaiting Analysis

Published: 2026-04-10T20:16:24.043

Modified: 2026-04-13T15:02:06.187

Link: CVE-2026-40190

cve-icon Redhat

No data.