Is CVE-2026-40190 actively exploited?

A proof-of-concept exploit is publicly available for CVE-2026-40190, but active exploitation has not been confirmed.

Can CVE-2026-40190 be exploited remotely?

Yes. CVE-2026-40190 is exploitable remotely over the network (CVSS attack vector: Network).

What is the CVSS score of CVE-2026-40190?

CVE-2026-40190 has a CVSS score of 5.6 (MEDIUM).

HOME VULNERABILITIESCVE-2026-40190

MEDIUMPOC

CVE-2026-40190

CWE-1321Published: April 10, 2026· Updated: Apr 13, 2026

5.6

CVSS v3.1

Official 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.

NVD Source

Technical Analysis

CVE-2026-40190 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.

A proof-of-concept (PoC) exploit exists for CVE-2026-40190. While not yet confirmed in active campaigns, the availability of PoC code increases exploitation risk substantially.