CVE-2026-40190: LangSmith Client SDKs provide SDK's for interacting with the LangSmith platform. Prior to 0.5.18, the LangSmith JavaScri…
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.
- Published by source
- 2026-04-10
- First seen by Reality Radar
- 2026-10-27
- Last verified
- 2026-10-27
Affected
- Manufacturer
- langchain
- Products
- langsmith
- Versions
- <0.5.18
- CPE
- cpe:2.3:a:langchain:langsmith:*:*:*:*:*:node.js:*:*
Whether your exact unit is affected depends on the model, serial number and region in the official notice.
What the official notice says
Risk: critical severity (CVSS 9.8)
Is this affecting you?
Add what you own or use and Reality Radar will tell you when official changes match it — with evidence and next steps.
Sources
- NIST National Vulnerability Database Tier A · official published 2026-04-10
Evidence ledger
Every piece of evidence we store is appended to a public hash chain, so later edits are detectable. Anyone can re-verify it.
| Entry | Kind | Observed | Evidence hash | Entry hash |
|---|---|---|---|---|
| #2140 | new | 2026-10-27 | 6b3c74a5e251…fa7574 | cfe8e70c624b…f29161 |
Chain head: #2286 e212558e872c…954bc1