CVE-2026-40190Medium· 5.6▾ SunlitLangSmith 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() …
▾ Sunlit zone — Low / medium · no exploitation signal
impact 30.8 · likelihood 0.1 · exploitation 0
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Exploit-prediction probability, daily snapshots since Jul 7.
Disclosure to exploitation, from the record and what we observed since indexing it.
Disclosed via NVD
Last analysed / modified upstream
0.2%
0.2% → 0.3%
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.
langsmith < 0.5.18Upgrade past the affected range:
langsmith 0.5.18Connected by shared product, vendor, weakness, or advisory.
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